What other people think of you is none of your business.

同意xiaoyu880702
可看成是 A is B.,其中
A是 What other people think of you,引导主语从句,“别人认为你怎么样”.原疑问句是What do other people think of you?,而助动词do在主语从句是不需要的
B是 none of your business,“与你无关”.新概念英文中有 It is none of your business.实际上,What other people think of you is none of your business 是 其扩展.