In this paper,firstly it makes a more detailed review and comment of the study of foreign IPO underpricing’s theoretical model and then to equity division reform for the occurrence of events. Were selected before and after the split share reform in China IPO companies as samples, Including IPO price and the success rate. Influencing factors on A multiple regression analysis. Final conclusion is that the equity division reform did not reduce the level of IPO underpricing, we should further inquiry system to achieve reform.