This article studies the relationship between CEO duality and corporate performance based on different ownership concentration. We divide the sample by cluster analysis into two subgroups, the high ownership concentration level subgroup and low ownership concentration level subgroup. After that, principal component analysis is employed to calculate the performance index based on an evaluation system which includes multiple dimensions and multiple indicators of firm performance. Finally, we conduct the regress analysis with the two subgroups to examine the relationship between duality and performance index on high and low degree of ownership concentration. The analysis of full sample indicates that there is no significant correlation between CEO duality status and performance. But duality has a positive effect on firm performance in the high degree of ownership concentration subgroup. There is no significant difference between corporations which set up board chairman and CEO in different way. This still doesn't not change the fact in high and low degree of ownership concentration.