With the appearance of socialist political economics with Chinese characteristics, the interest analysis method of socialist political economics with Chinese characteristics presents a contemporary evolvement in the inheritance and development of Marx’s interest analysis method. The interest analysis method of socialist political economics with Chinese characteristics is overall used in the construction of socialist economics with Chinese characteristics, and it reflects the dialectical unity of the theoretical logic and historical logic. As the new change of socialism with Chinese characteristics at the new era, the principal contradiction facing Chinese society has evolved to the contradiction between unbalanced and inadequate development and the people’s ever-growing needs for a better life. Based on the interest analysis method of socialist political economics with Chinese characteristics, we can find that the new interest imbalance formed in the old normal development is the intrinsic motivation of evolvement of the principal contradiction facing Chinese society at the new era.