In view of the default risk of enterprises, this paper uses KMV model for empirical analysis based on the market information of technology-based enterprises on the main board and gem, and calculates the default distance and default probability of technology-based enterprises of different sizes. On this basis, the sensitivity analysis of the factors affecting the default risk is carried out to explore the influence of each factor. Finally, according to the results of empirical analysis, the paper puts forward suggestions for the financing system and risk management of the government, financial institutions and enterprises.