Abstract: To explore the synergistic effects between different environmental regulatory policies and maximize the motivation for green innovation among supply chain enterprises, game theory and decision optimization methods are used to investigate the market performance and social green performance of green supply chains with two governance strategies of government subsidies and carbon emission reduction regulations from the perspective of joint innovation. Considering carbon emission reduction constraints per unit green product, K-T conditions are introduced to establish and solve the government subsidy models with manufacturer individual innovation (IM) and joint innovation (UG). Results are then compared and analyzed. It is found that only when the carbon emission reduction constraint exceeds a certain threshold can the dual governance strategy be effective, otherwise only the subsidy strategy is effective. Compared to the single subsidy strategy, the dual governance strategy can achieve a higher level of carbon emission reduction per unit of product, which helps to increase the market demand for green products. However, it does not benefit the profits of manufacturers, and does not fully leverage the advantage of the joint innovation model. The two governance strategies have positive synergistic effects in improving consumer surplus and total social welfare, but negative synergistic effects in realizing the social value of joint innovation.