Umm, lots of modification required here.
Within the partial view you need to call the same partial view (recursive), but your inner partial view will have the sub categories.
First you load the partial view for the category and within that partial view you called the same view for the subcategory.
Please refer this thread -
http://stackoverflow.com/questions/16505300/loop-through-multi-level-dynamic-menus-in-asp-net-mvc[
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-KR