The theory of situated learning as legitimate peripheral participation(LPP)is widely applied in the educational field.But understandings of it are diversified so that quite a lot of these understandings in literature are not in conform to the spirit of the theory.Thus,drawing on literature review,this paper attempts to explicate the theory from three aspects:practical and philosophical base,the central ideas of the theory,and its difference from the cognitive learning theory,aiming to contribute to an easier understanding of it by readers and researchers.