Cost reduction and efficiency enhancement is one of the important initiatives to deepen the reform of SOEs and achieve the goal of making SOEs stronger, better and larger. This paper systematically examines the impact of government intervention on cost stickiness of enterprises and its mechanism of action, using a Differences-in-Differences model, basing on a quasi-natural experiment exogenous event, the effective implementation of the slimming and fitness reform, which was recognized and adopted by the State Council in 2016. The empirical findings show that the implementation of slimming and fitness reform has a significant inhibitory effect on SOEs' cost stickiness, and this finding holds after a series of robustness tests including parallel trend hypothesis test, propensity score matching test, and placebo test and so on. It is further found that this phenomenon of significant suppression of cost stickiness in SOEs by the slimming and fitness reform does not change significantly by differences in SOEs' hierarchy, profitability, and degree of market competition. The channel research finds that the phenomenon of significant suppression of cost stickiness in SOEs by the slimming and fitness reform exists regardless of the transparency of information environment and asset specialization, but it is more pronounced in SOEs with lower information transparency and higher asset specialization. This study not only enriches the research on the economic consequences of SOE reforms and expands the literature on the factors influencing cost stickiness in enterprises, but also helps to provide policy recommendations for promoting supply-side structural reform from the perspective of cost reduction and efficiency improvement in SOEs.