Abstract: Under the background of China's ongoing pursuit of its “ dual-carbon” goals, exploring how to leverage thepolicy demonstration and dilliusion ellects of voluntary environmental regulations to curb corporate "greenwashing” behaviorsholds significant theoretical importance for promoting high-quality green transformation of enterprises. This study utilizesdata from A-share listed companies (2013-2023 ) and employs a multi-period difference-in-dierences ( DlD) modeltreating the Green Factory Demonstration Project initiated by the Ministry of Industry and Information Technology ( Ml'T) asan exogenous policy shock. We empirically examine how green factory certification inhibits greenwashing among local, un.regulated peer enterprises and explore the underlying mechanisms. The study finds that green benchmarks ( enterprises se.lected for the green factory project) exhibit obvious policy incentive and demonstration effects, which can significantly re.duce the degree of “ greenwashing” among local unregulated enterprises and promote their substantive greentransformation. These results remain robust across multiple sensitivity tests. Mechanism analysis indicates that green factorycertification suppresses greenwashing through three channels: network spillover effects, competitive incentive effects, andlearing effects. Heterogeneity analysis shows stronger inhibitory impacts on state-owned enterprises ( SOEs), manufactur.ing firms, and companies in regions with weaker environmental regulations. Furthermore, the certiication exhibits verticaspilover elfects along the supply chain, curbing greenwashing among upstream and downstream partners. This study expands the research boundaries of voluntary environmental regulation elfectiveness, provides novel evidence and insights forleveraging green benchmarking to combat industry-wide greenwashing, and olers practical implications for advancing cor.porate green information disclosure and substantive sustainability transitions.

Key words: green factory, voluntary environmental regulation, greenwashing, spillover effects