Park city policy is an exploration of the construction of urban ecological civilization under the background of the new era of China. The evaluation of the economic performance is an important step to improve and popularize this policy. The article takes the implementation of the policy in Chengdu, China, as a quasi-natural experiment and adopts the penalized version of a synthetic control method to evaluate the economic performance of the policy. Firstly, the results show that park city policy improves economic performance by prompting the aggregation of labor factors and innovators, optimizing the structure of the local industries, and bringing an investment multiplier effect. Secondly, by establishing the control group, the penalized version of the synthetic control method is effective in overcoming the endogeneity and evaluating the economic performance of the policy. Thirdly, park city policy has significantly positive effects on both the economy and the industrial structure of Chengdu. Based on the result, the related suggestions are proposed.