Whether the orientation of Chinese social behavior is collectivism or individualism is considerable problem which has brought about a lot of debates. This paper, from the perspective of social psychology, agures that the determinative elements of the orientation are neither the familism nor Confucianism, but four elements' matches one another by comparing the family structure of Chinese, Japanese, and westen societies. The four elements are (1) pernalism, (2) moral norm, (3) interests' distribution, (4) blood relationships. Since Japanese and westen families have not the four elements totally, their social behavior tends to be collectivist or individualist definitely, while in the course of Chinese social interaction, because of the matches of the four elements, Chinese social behavior becomes flexible and situational, which is shifted between collectivism and individualism. This paper offers a new theory in explaining the Chinese social behavior.