Based on the samples of the listed companies injected assets by big shareholders during 20032008, this paper examines the effect of equityspilt reform on the motivation of assets injection of big shareholders, and the results show that the motivation for big shareholders to obtain private benefit by using assets injection is obviously declining after sharesplit reform but to constantly inject their good assets to the listed companies to improve the performance of the companies, and that before sharesplit reform, the big shareholders of private listed companies use assets injection to infringe medium and small shareholders but after sharesplit reform, the interests conflict between big shareholders and medium and small shareholders in private companies is mitigated. Thus, the change of the motivation of assets injection of big shareholders in private companies is stronger than that of stateowned companies after sharesplit reform. 