Abstract: The focus of the debate on the effect of industrial policy from all walks of life nowadays is not limited to the problem itself, but to the boundary of the effect of industrial policy. The new energy vehicle industry is a hot area of policy formulation in various countries, and scholars have conducted bountiful research on the evaluation of policy effect. However, as well as the evaluation of policy effect research in other area, there are also fragmented and incomparable research dilemmas in the fields of new energy vehicle industry. Seeking research breakthroughs from methodological innovation on the causes of the differences of the evaluation results of industrial policy is of great significance to promote policy evaluation theory and improve the content of industrial policy. It is particularly urgent to systemically sort out the current complex evaluation elements and find out a deeper explanation for the debate of conclusion of the evaluation of policy effect. The systematic review method optimizes the deviation of literature identification, selection and conclusion through the critical secondary analysis of existing research results to achieve in-depth analysis of specific topics. The method is used to collect articles whose research theme is the evaluation of policy effect on the new energy vehicle industry from 2009 to 2020 from Web of Science. After removing irrelevant data, 175 articles are obtained as research samples. According to the framework of the policy evaluation system and the basic relationship between the evaluation elements from the existing research, the samples are sorted out. The components of evaluation system of the policy effect on the new energy vehicle industry are identified, and the causes of the different conclusions on the evaluation of policy effect are discussed based on the research results. Adopting control variable method, the study compares the impact of different evaluation element and specific evaluation element on the conclusion of evaluation of policy effect one by one. The evaluation standard include the standard of the fact dimension (efficiency, efficiency, adequacy) and the standard of the value dimension(fairness, responsiveness, adaptability);The evaluation environment includes four categories: political environment, economic environment, social environment and technological environment; The evaluation subjects includes stakeholders and independent third parties; The evaluation object includes supply side policy tools (tax relief for producers subsidies, production subsidies, emission standards, industrial planning, etc.) and demand side policy tools (tax relief for consumers, purchase subsidies, government purchases, privileges of using, subsidies of using, etc.);The evaluation method includes qualitative evaluation methods and quantitative evaluation methods. The evaluation model includes positivism, constructivism and critical positivism. Each evaluation element has its impact on the evaluation results and specific evaluation element does its job to the diverse conclusions of the evaluation of policy effect. The following conclusions are drawn: (1) The elements of the evaluation of policy effect on the new energy vehicle industry can be classified into six categories: evaluation standard, evaluation environment, evaluation subject, evaluation object, evaluation method, and evaluation model. (2) The difference in the combination of evaluation factors is an important reason for the different conclusions of the evaluation of policy effect on the new energy vehicle industry. The evaluation model is the "strategic deployment" of the evaluation. Once determined, the selection of other evaluation elements is restricted. The numerous combinations of specific evaluation element have an effect on the difference of evaluation conclusions. The application of this methodology provides a new research idea to solve the dilemma of the evaluation of policy effect, and promotes the optimization of evaluation of policy effect on the new energy industry; To the evaluation system, it provides a research perspective for exploring the boundary where industrial policies work.

Key words: systematic review, the evaluation of policy effect, new energy vehicle industry, policy evaluation system