Abstract: Based on the study of structure and principle of KPX series water regulator and the investigation of relevant literature’s at home and abroad, this paper polnts out the main reasons of low pulling and running success ratio, which include improper seal structure of eccentric hole and blanking plug, unreasonable return spring, and effect of fishing rod on cam. This paper discusses the construction rationality of KPX eccentric self-regulating water regulator developed in Qinghai Oilfield. The effectiveness of higher pulling and running success ratio has been obtained in field application of new type injection mandrel.