diff --git a/docs/sphinx_doc/_templates/package.rst_t b/docs/sphinx_doc/_templates/package.rst_t
index 1b96b977d..33de86a3f 100644
--- a/docs/sphinx_doc/_templates/package.rst_t
+++ b/docs/sphinx_doc/_templates/package.rst_t
@@ -16,7 +16,7 @@
 {%- if is_namespace %}
 {{- [pkgname, "namespace"] | join(" ") | e | heading }}
 {% else %}
-{{- pkgname | e | heading }}
+{{- pkgname | join(" ") | e | heading }}
 {% endif %}
 
 {%- if is_namespace %}
@@ -27,6 +27,10 @@
 {{ automodule(pkgname, automodule_options) }}
 {% endif %}
 
+{%- if subpackages %}
+{{ toctree(subpackages) }}
+{% endif %}
+
 {%- if submodules %}
 {% if separatemodules %}
 {{ toctree(submodules) }}
diff --git a/docs/sphinx_doc/source/data_juicer.analysis.rst b/docs/sphinx_doc/source/data_juicer.analysis.rst
index 38ae941e3..a5574a097 100644
--- a/docs/sphinx_doc/source/data_juicer.analysis.rst
+++ b/docs/sphinx_doc/source/data_juicer.analysis.rst
@@ -1,5 +1,5 @@
-data\_juicer.analysis
-=====================
+d a t a \_ j u i c e r . a n a l y s i s
+========================================
 
 
 data\_juicer.analysis.column\_wise\_analysis
diff --git a/docs/sphinx_doc/source/data_juicer.config.rst b/docs/sphinx_doc/source/data_juicer.config.rst
index e4c94cb68..ad39f8e43 100644
--- a/docs/sphinx_doc/source/data_juicer.config.rst
+++ b/docs/sphinx_doc/source/data_juicer.config.rst
@@ -1,5 +1,5 @@
-data\_juicer.config
-===================
+d a t a \_ j u i c e r . c o n f i g
+====================================
 
 
 data\_juicer.config.config
diff --git a/docs/sphinx_doc/source/data_juicer.core.rst b/docs/sphinx_doc/source/data_juicer.core.rst
index 0bfeb79fb..9fa73b8a2 100644
--- a/docs/sphinx_doc/source/data_juicer.core.rst
+++ b/docs/sphinx_doc/source/data_juicer.core.rst
@@ -1,5 +1,5 @@
-data\_juicer.core
-=================
+d a t a \_ j u i c e r . c o r e
+================================
 
 
 data\_juicer.core.analyser
diff --git a/docs/sphinx_doc/source/data_juicer.format.rst b/docs/sphinx_doc/source/data_juicer.format.rst
index 70f783fbf..ba772be8f 100644
--- a/docs/sphinx_doc/source/data_juicer.format.rst
+++ b/docs/sphinx_doc/source/data_juicer.format.rst
@@ -1,5 +1,5 @@
-data\_juicer.format
-===================
+d a t a \_ j u i c e r . f o r m a t
+====================================
 
 
 data\_juicer.format.csv\_formatter
diff --git a/docs/sphinx_doc/source/data_juicer.ops.common.rst b/docs/sphinx_doc/source/data_juicer.ops.common.rst
index 3f7b6fad9..3d9df69c9 100644
--- a/docs/sphinx_doc/source/data_juicer.ops.common.rst
+++ b/docs/sphinx_doc/source/data_juicer.ops.common.rst
@@ -1,5 +1,5 @@
-data\_juicer.ops.common
-=======================
+d a t a \_ j u i c e r . o p s . c o m m o n
+============================================
 
 
 data\_juicer.ops.common.helper\_func
diff --git a/docs/sphinx_doc/source/data_juicer.ops.deduplicator.rst b/docs/sphinx_doc/source/data_juicer.ops.deduplicator.rst
index 73cdd733d..f65db96fe 100644
--- a/docs/sphinx_doc/source/data_juicer.ops.deduplicator.rst
+++ b/docs/sphinx_doc/source/data_juicer.ops.deduplicator.rst
@@ -1,5 +1,5 @@
-data\_juicer.ops.deduplicator
-=============================
+d a t a \_ j u i c e r . o p s . d e d u p l i c a t o r
+========================================================
 
 
 data\_juicer.ops.deduplicator.document\_deduplicator
diff --git a/docs/sphinx_doc/source/data_juicer.ops.filter.rst b/docs/sphinx_doc/source/data_juicer.ops.filter.rst
index b904f3ddb..6606bd3e8 100644
--- a/docs/sphinx_doc/source/data_juicer.ops.filter.rst
+++ b/docs/sphinx_doc/source/data_juicer.ops.filter.rst
@@ -1,5 +1,5 @@
-data\_juicer.ops.filter
-=======================
+d a t a \_ j u i c e r . o p s . f i l t e r
+============================================
 
 
 data\_juicer.ops.filter.alphanumeric\_filter
diff --git a/docs/sphinx_doc/source/data_juicer.ops.mapper.rst b/docs/sphinx_doc/source/data_juicer.ops.mapper.rst
index 16941ecfd..69f8ceea5 100644
--- a/docs/sphinx_doc/source/data_juicer.ops.mapper.rst
+++ b/docs/sphinx_doc/source/data_juicer.ops.mapper.rst
@@ -1,5 +1,5 @@
-data\_juicer.ops.mapper
-=======================
+d a t a \_ j u i c e r . o p s . m a p p e r
+============================================
 
 
 data\_juicer.ops.mapper.clean\_copyright\_mapper
diff --git a/docs/sphinx_doc/source/data_juicer.ops.rst b/docs/sphinx_doc/source/data_juicer.ops.rst
index a9546d875..46e9ed19a 100644
--- a/docs/sphinx_doc/source/data_juicer.ops.rst
+++ b/docs/sphinx_doc/source/data_juicer.ops.rst
@@ -1,5 +1,14 @@
-data\_juicer.ops
-================
+d a t a \_ j u i c e r . o p s
+==============================
+
+.. toctree::
+   :maxdepth: 4
+
+   data_juicer.ops.common
+   data_juicer.ops.deduplicator
+   data_juicer.ops.filter
+   data_juicer.ops.mapper
+   data_juicer.ops.selector
 
 
 data\_juicer.ops.base\_op
diff --git a/docs/sphinx_doc/source/data_juicer.ops.selector.rst b/docs/sphinx_doc/source/data_juicer.ops.selector.rst
index dc8965e81..0e796dbf6 100644
--- a/docs/sphinx_doc/source/data_juicer.ops.selector.rst
+++ b/docs/sphinx_doc/source/data_juicer.ops.selector.rst
@@ -1,5 +1,5 @@
-data\_juicer.ops.selector
-=========================
+d a t a \_ j u i c e r . o p s . s e l e c t o r
+================================================
 
 
 data\_juicer.ops.selector.frequency\_specified\_field\_selector
diff --git a/docs/sphinx_doc/source/data_juicer.rst b/docs/sphinx_doc/source/data_juicer.rst
index e4b82ca52..1d7ba53b1 100644
--- a/docs/sphinx_doc/source/data_juicer.rst
+++ b/docs/sphinx_doc/source/data_juicer.rst
@@ -1,2 +1,13 @@
-data\_juicer
-============
+d a t a \_ j u i c e r
+======================
+
+.. toctree::
+   :maxdepth: 4
+
+   data_juicer.analysis
+   data_juicer.config
+   data_juicer.core
+   data_juicer.format
+   data_juicer.ops
+   data_juicer.tools
+   data_juicer.utils
diff --git a/docs/sphinx_doc/source/data_juicer.tools.rst b/docs/sphinx_doc/source/data_juicer.tools.rst
index 6d25049a6..6890d94e3 100644
--- a/docs/sphinx_doc/source/data_juicer.tools.rst
+++ b/docs/sphinx_doc/source/data_juicer.tools.rst
@@ -1,2 +1,2 @@
-data\_juicer.tools
-==================
+d a t a \_ j u i c e r . t o o l s
+==================================
diff --git a/docs/sphinx_doc/source/data_juicer.utils.rst b/docs/sphinx_doc/source/data_juicer.utils.rst
index 8a724caf1..22a810cc3 100644
--- a/docs/sphinx_doc/source/data_juicer.utils.rst
+++ b/docs/sphinx_doc/source/data_juicer.utils.rst
@@ -1,5 +1,5 @@
-data\_juicer.utils
-==================
+d a t a \_ j u i c e r . u t i l s
+==================================
 
 
 data\_juicer.utils.asset\_utils