Relationship between top managers' social capital and their firm performances and the contingency role of environmental uncertainty were exploded by using 438 effective questionnaires from Chinese firms and deep interviews with 14 Chinese top managers.  The results show that the social capitals of the top managers could be divided into two categories, the market social capital and nonmarket social capital and the both of them would improve firms' performances significantly.  Compared with the market social capital, the top nonmarket social capital of the top managers would play the more significant role in improving firm performances in the more complex environment; compared with the nonmarket social capital, the top managers' market social capital would play the more significant role in improving the firm performances in the more turbulent environment.