Promoting digital transformation of enterprises is an inevitable requirement for achieving high-quality economic development. Command-and-control environmental regulations represented by low-carbon city pilot policies play an important role in the construction of "digital China". Based on the pilot policy of low-carbon cities as the entry point, data from China' A-share listed companies from 2007 to 2021 was used to test the impact and mechanism of command-and-control environmental regulation policies on enterprises' digital transformation by the staggered differential model. The results show that the implementation of pilot policies in low-carbon cities can effectively force enterprises to transform digitally by reducing carbon emission level, promoting green technology innovation, easing financing constraints and adjusting from directors' overseas background. The conclusion is still valid after a series of robustness tests. The heterogeneity analysis shows that the policy effect will depend on the difference of industry type and category of employment. Further analysis shows that while promoting digital transformation, the policy can also promote the expansion of enterprises and the economic development of pilot areas. The economic contribution of pilot cities is 0. 0184%. The research conclusions of this article have important implications for how the government use macro-control means to force enterprises to digital transformation and realize the coordinated development of "green" and "digital" economy.