After the formation of the Chinese green bond market in 2016, it rapidly developed. However, there have been relatively few studies in academia on the financial performance of enterprises after issuing green bonds. In order to promote the development of the green bond market and guide enterprises to improve their investment and financing decisions, this paper uses panel data of A-share listed companies and green bond issuing companies from 2012 to 2022 as samples to study the impact and mechanism of green bond issuance on the investment and financing behavior and maturity mismatch of enterprises. The conclusion drawn is that green bond issuance significantly promotes the improvement of enterprises' investment and financing capabilities, and it also reduces the degree of maturity mismatch for enterprises. This conclusion passes the parallel trends test and remains robust after controlling for the effects of corporate financial asset allocation, industry time trends, and excluding competitive hypotheses. Through mechanism research, it is found that green bonds can improve the level of enterprise investment and financing and the degree of maturity mismatch by reducing the degree of financing constraints on enterprises. They can also enhance enterprise investment and financing capabilities by changing market sentiment and alleviate the maturity mismatch of investment and financing.