Making environmental regulation (ER) in line with local development reality is the key to promoting regional coordinated development. Current research mainly concentrates on the overall effect of ER or the policy effect of some specific regulations. In reality, the ERs are not always one-size-fits-all, and the evaluation of the biased ER’s effect is mostly overlooked. This paper takes the biased energy-saving policy (BESP) of 13th Five Year Plan as an example and identifies the impact of the BESP on enterprises’ total factor productivity (TFP) based on a Difference-in-Difference model. Our results suggest that the BESP has significant promotion on the enterprises’ TFP. When considering the heterogeneity of enterprise and industrial characteristics, it can be found that large-scale, stateowned enterprises as well as enterprises with capital-intensive show more significant promotion effect from the BESP. Moreover, enterprises in high-energy consumption and low-tech industries also reveal more significant policy effect. Further, the results of the mechanism analysis indicate that the BESP promotes the enterprises’ TFP mainly through enhancing technical-focused investment preference and narrowing technical gap within the industry. Our research fills the gap in the study of biased ER, which provides a new orientation for realizing the carbon neutrality goal.