Hai, I have heard about adaptive radiation so what i would like to ask is that can we call human evolution as adaptive radiation ..

Adaptive radiation is where an ancestral form adapts to multiple niches, resulting in many related populations with different life styles. I don't think that this can be used to describe humans. Yes we have spread all over the world, and there had been some superficial adaptation, such as skin colour or lung size, but I'm not sure it could be called adaptive radiation. We are still one species, we can all interbreed. Another way of looking at it is that with only a few exceptions most of humaity occupies the same basic niche, that of the dominant animal, the hunter and farmer. In general, we all like to live on the same kinds of land; where there is water, good soil and any natural resources we can exploit.