At the expiration of the first round of "Double FirstClass" construction, it is of practical significance to evaluate policy effects of building worldclass universities. After summarizing evaluation dimensions of policy effects of building worldclass universities, by collecting panel data of 39 world firstclass universities construction universities and 57 world firstclass disciplines construction universities from 2015 to 2019 and constructing the econometric model with the differenceindifferences method, this study evaluates policy effects of building worldclass universities. The research finds that the implementation of the policy of building worldclass universities has positive impacts on selected universities in terms of the comprehensive strength, discipline construction, faculty construction, and social service capability, and estimated values of policy effects are statistically significant and pass a series of robustness tests in general. However, the policy of building worldclass universities has positive but insignificant impacts on selected universities in a few indicators, which reflects some gaps and deficiencies of policy effects compared with policy objectives. Therefore, the study puts forward some policy suggestions in the new round of building worldclass universities: to pay attention to characteristic and humanistic disciplines in terms of discipline construction; to focus on "endogenous" development and combine "internal sources" and "external assistance" in terms of faculty construction; to build a longterm and effective mechanism for the transformation of scientific and technological achievements in terms of the improvement of social service capabilities.