In this study, the author reviews the developing process of INSET in England since 1970, and makes critics its influence. The INSET in England has changed from traditional centralizes model to the social market model since Local Education Authority training Grant Scheme(LEATGS) was put into practice in 1986. The social market model complied with the demand-supply principle of free competition in one hand, and reinforced by the influence of government at the other; therefore, this model brings tremendous impact to the INSET infrastructure, its development and management. This present study demonstrates the influence of INSET policy under social market model to the INSET education in England by analyzing the changing function of Local Education Authority(LEA) and Teachers Centre (TC), which play major roles under the traditional centralized model. On the aspect of INSET development and management, critique on "teacher-centered" model in LEATGS are also presented. The final part of the study provides suggestions to domestic INSET policy, the establishment of INSET infrastructure and teacher centers in local areas.