In this article, in-depth analysis was made on the relations between the dialectical thinking of 'Taixuan' and 'Yizhuan'. The Yin and Yang theory of 'Yizhuan' was explained as the theory of the growth and decline of Yin and Yang (Yin Yang Xiao Xi Theory). The thinking of in-the-process was discussed and elevated into a theoretical level. And it was endowed with more metaphysical character and meanings of Weltanschauung. The theory on the interaction between the strong and the weak was further explained. The subject matter of the interaction between and weighty Yin and ethereal Yang was put forward. This article also discussed the theory of 'things going into their opposites after becoming too extreme'. The Shizhong (Do the right all the time) theory of Yizhuan was explained more explicably. The dialectic category was enriched by putting forward the theory of 'complementation between following the old tings while modifying them'. The author deemed that Taixuan, soaking up both the Yi and Lao, had made important contribution to the development of Chinese ancient dialectical thinking.