Abstract: The discussion on the evaluation of verificationism in the development of Wittgenstein philosophy recently attracts more attention in the field.For a better understanding,several perspectives in interpreting verificationism should be taken into account,including the relation of verification and its early philosophy,the features of middle philosophy and the embodied theoretic meaning of verificationism.It is a feasible approach to summarize and analyze the related documented studies abroad.Different characteristics of verificationism were found in the early and late philosophy.First,verificationism formed the critique on the early philosophy in terms of the relation of language and reality.Second,as the middle philosophy changed gradually,verificationism changed its content and reflected interacting of various ideas during the middle philosophy.Third,verificationism is partly related method of verification to the meaning of sentences,which differentiated from the Vienna Circle's way to determine the meaning of sentences.This paper demonstrates that the different interpreting of verificationism reflected the different understanding of Wittgenstein's middle philosophy.Due to the indeterminacy of its content and its dependence upon middle philosophy,verificationsim was finally declined by Wittgenstein when he moved forward into his late philosophy.However,it is indispensable from the understanding of middle philosophy and even the whole philosophy of Wittgenstein without verificationism.

Key words: Wittgenstein's middle philosophy, verificationism, Tractatus Logico-Philosophicus, phenomenological language, philosophical grammar