With the rapid development of China's green bond market, state-owned enterprises have accounted for 68% of the issuance share, playing a crucial role in achieving the "dual carbon" goals. However, whether the green bond funds are truly and effectively used for environmental improvement projects and whether there is "greenwashing" behavior have become the focus of market and policy attention. Based on the signal transmission theory and the resource dependence theory, this paper constructs a theoretical framework for the impact of green bond issuance on the environmental performance of enterprises, and conducts empirical tests using panel fixed effect models, propensity score matching method (PSM), and case analysis method. The research results show that green bond issuance can significantly improve the environmental performance of state-owned enterprises, especially in high-pollution industries and large enterprises. The mechanism test reveals that green bonds reduce financing costs and increase environmental protection investment, thereby promoting the improvement of environmental performance. This study provides theoretical basis and practical references for the government to optimize green financial policies, enterprises to implement green transformation, and investors to identify high-quality green bonds.