Enterprise innovation is a hot topic in current academic research. Taking the demonstration city of social credit system construction implemented in China as a quasi-natural experiment, this paper investigates whether the construction of social credit system can improve enterprise innovation. The study finds that the construction of social credit system effectively enhances enterprise innovation. Mechanism test shows that the construction of social credit system escalates the scale and duration of enterprise loans, thereby fostering enterprise innovation. These findings present insights that the pivotal role of informal institutions, such as the social credit system, in facilitating the upgrading of industrial structures and augmenting the quality of economic development.