This paper proposes the big five social system traits as the fixed, clear, and workable social solutions to the social issues under the different social conditions. Under the big five social system traits, different fixed and clear personal behaviors are developed by different people under different social conditions, so the big five social system traits are the source of different aspects of human behavior in terms of personality traits in the big five personality traits, personality types in the MBTI, social styles in the social style model, personality disorders in the DSM-5, social group deviances derived from the DSM-5, and religious, political, and economic systems in Western and Eastern cultures as described in this paper. The big five social system traits consist of sociality (individualistic-collectivistic-interdependent) traits to the issue of social formation, worldview traits (connective-competitive-territorial or people-tasks) to the issue of social boundary, awareness traits (concrete-imaginary) to the issue of social stress, activity traits (constructional-mobilized) to the issue of social duration, and legitimacy traits (authoritative-rational) to the issue of social uniformity. As a result, the big five social system traits provide the base for the unified theory of human behavior to unify different aspects of human behavior and to produce the common ground for diverse views to communicate.