To enhance the construction efficiency of small-diameter tunnel boring machine(TBM) and to accurately predict the service life of disc cutters, a life prediction model for small-diameter TBM disc cutters was developed. This model integrated mathematical statistics with multiple regression analysis and was tailored for different rock mass categories. Taking the historical statistical data of tool replacement in the TBM2 section of Tianshui Quxi diversion tunnel as the research object, the wear forms of rolling cutters in different areas of the cutterhead and the evolution law of wear rate per unit rock breaking volume of each cutting position were analyzed. The average life of rolling cutters based on cumulative tool replacement times was obtained. Using single parameter nonlinear fitting and multiple linear regression analysis, the correlation between four excavation parameters and rolling cutter life was explored. The findings revealed that excavation parameters are inversely related to disc cutter life through a power function, with penetration being a significant factor affecting disc cutter life. The model demonstrated high stability and interpretability in class Ⅲ and Ⅳ rock masses, where the R² for class Ⅲ rock mass exceeded 90%. However, in class Ⅴ rock mass, the model faced more pronounced collinearity issues due to limited data, resulting in reduced predictive.