@lisuwang It would be great to setup a ROS China User Group. To get it going please create a proposal in the site feedback category: https://discourse.ros.org/c/site-feedback similar to how there was the recent proposal for the ROS Brazil User Group proposal here. If you can gather together a group of people who can express interest in participating and leading discussions in the category though adding supportive comments on the thread we can create it.
In general we are looking to make sure that there will be an active community that can maintain enough inertia to build and grow the community. Creating too fine grained subcategories w/o inertia in them can lead to disappointing experiences of new users. I also believe that there are some ROS groups on WeChat and other Chinese language sites and the feedback that I’ve received is that those are preferred over our hosting them. If there’s demand we would be happy to support having a dedicated sub category here.