This paper believes that the basic principle which May 4 th new culture movement advocates is rational egoism and individualism. Its theoretical foundation is humanity and ethics on the basis of seeking happy without suffering. The individualism will be discussed in detail in the paper. This paper believes that the basic principle which May 4 th new culture movement advocates is rational egoism and individualism. Its theoretical foundation is humanity and ethics on the basis of seeking happy without suffering. The individualism will be discussed in detail in the paper.