Abstract: This paper explored the evolution principle and impact factors of A share firms’ board structure with firm’s life cycle by constructing the firm’s life cycle index according to industry method. The results show that the board size of Chinese A share listed firms is decreasing with firm’s life cycle, and the board leadership is separating with firm’s life cycle, but the board independence is almost static. The advising hypothesis of board structure that the adjustment of board structure of Chinese A share listed firms is most based on resources afforded by the new added board members is evidenced by the findings, while the monitor hypothesis is not well validated.