Considering institutional investors’self-protection，a game model between insiders and institutional investors is built to reveal the micro mechanism how institutional holdings influence corporate performance． An empirical test is performed on the listed firm samples in Shanghai and Shenzhen A Stock Market between 2004 ～ 2012． The results show the structural change of the effects of institutional investors on corporate per-formance during the first period ( 2004 － 2007) and the second one ( 2008 － 2012) ． The results also show that although during these two periods the institutional investors as a whole had positive effects on corporate per-formance，the effect in the second period was obviously weaker than in the first period． The mutual fund hold-ings rather than the other institutional holdings could improve corporate performance． The main reason is that during the sample period，the holding ratio of the mutual fund decreased and the ratio of other institutional in-vestors increased rapidly，which resulted in the overall weakening of the positive effect of the institutional in-vestors on corporate performance．