The emergence of abnormal economic makes people pay more attention to the problem of economic complexity. The basic hypothesis of the traditional economic theory has been questioned，as the same time，the theory of economic complexity rise up. Abnormal economic phenomenon no longer mystery，the complexity of the microscopic agent behavior is the main reason of economic complexity. Bases on the microscopic agent behavior，this chapter analysis the key behavior characteristic deeply，puts forward the suitable economic model to analysis microscopic agent behavior，and explores the effective ways to solve the problem of economic complexity.