Government data opening is a necessary measure for the supply of data factors，and using government data opening to enhance urban entrepreneurial activeness is an important path and embodiment of releasing data dividends. In this paper，government data opening was used as a quasi-natural experiment，and the progressive double-difference method was used to test the impact of data factors supply on urban entrepreneurial activeness. It was found that the supply of data factors represented by government data opening can significantly improve the entrepreneurial activeness in cities. The mechanism analysis showed that government data opening enhances urban entrepreneurial activeness by promoting technological innovation，strengthening talent gathering and improving government administrative efficiency. The heterogeneity analysis showed that the promotion effect of government data opening on urban entrepreneurial activeness is more obvious in cities with higher financial development level，digital economy development level and economic development level，as well as producer services. Further analyses showed that there is a positive correlation between the open quality of government data and the entrepreneurial activeness in cities，and the open government data improves the entrepreneurial quality in cities. This paper will enrich the research on the economic effect of data factor supply and clarify the logical mechanism of government data opening to enhance urban entrepreneurial activeness，and provide theoretical basis and decision-making reference for enhancing the positive effect of government data opening on urban entrepreneurship.