Abstract: Project performance appraisal is a technical economy activity that systematically and objectively analyses and summarizes the effectiveness, benefit and influence of a project after operating for some time. Making use of success degree evaluation methodology, this paper sets up basic model for success degree evaluation methodology and makes grade estimation on evaluating indexes for the project of improving irrigation agriculture through loaning from World Bank. Meanwhile, it level analyzes all indexes to get weighing values and assess outcome according to the general performance of this project. Success degree evaluation methodology boasts of objectively scientific appraisal of benefit, summarizing experience and providing consultation for the project of improving irrigation agriculture through loaning from World Bank, even the decision, construction and management of general development of agriculture.