This paper attempts to investigate the relationship between accounting firm organizational transformation and IPO underpricing，and the auditor reputations effect on the relationship above from the view of audit demand side in the IPO market.The study found that，with the gradual implementation of accounting firm organizational transformation policy，the IPO underpricing of companies audited by special general partnership firm is higher.At the same time，the auditor reputation will weaken the relation between accounting firm organizational transformation and IPO underpricing.These phenomena indicate that accounting firm organizational transformation has obtained the acceptation of investors in the IPO market，and the firms which have a low reputation acquire more greatly enhance in its brand value with the restructuring of the special general partnership.