This paper analyzes the influence of shareholder structure reform on the interests of mass investors by taking 45 exper- imental companies and listed companies on medium-sized and small panel as examples.The results indicate that the shareholder structure reform changed shareholder structure of the companies,that the biggest shareholder obviously reduced shareholding pro- portion,that the second-level shareholder has stronger restriction on the biggest shareholder,the share-holding value of pres- ent investors is raised,and that,however,the performance of the listed companies is not obviously changed.Whether the share- holder structure reform can increase value of shares needs to be tested.