Sub category post not display in category

You mean in your category posts lists? So in a category page of posts, you don’t want your subcategories to be posted as well?

This is what I am looking for too.

You could create a template for this category and then use query_posts to exclude the sub-categories.

http://codex.wordpress.org/Category_Templates
http://codex.wordpress.org/Template_Tags/query_posts

That plugin, Just one category, is also here:
http://wordpress.org/extend/plugins/just-one-category/