The construction of key projects during the “First Five-Year Plan” period has laid the foundation for China’s industrial development, and many cities have undergone great changes in infrastructure and urban patterns, and at the same time, it has also accumulated rich and valuable Chinese experience and Chinese wisdom. In this paper, the effect of national macro policies on the implementation of Lanzhou City during the “First Five-Year Plan” period is investigated. First, the impact of national macro policies on the construction of key projects in Lanzhou City is estimated by using the multi-period double-difference model, which shows that the estimated coefficients of the engineering construction variables in Lanzhou City are significantly negative at the level of 1 percent. Secondly, combined with the multi-period double difference model, parallel trend test, robust estimator of heterogeneity, and placebo test are used to verify the robustness of the conclusions obtained from the benchmark regression, and the results show that the conclusions obtained from the benchmark regression are robust. The study of heterogeneity of policy effects shows that, subregionally, national macro-policies have a more pronounced role in promoting economic growth in the western region of Lanzhou, where key projects are being constructed, with a smaller impact on the eastern region, and a statistically insignificant role in the central region.