Abstract: The assembly process of the machine tool feed mechanism is the process of forming its assembly quality. Due to the influence of the 5M1E factor, the assembly process capability of the feed mechanism may be insufficient, which can lead to significant fluctuations in the assembly quality of the feed mechanism, and even unqualified products. Therefore, based on the theory of C_pu and Bootstrap, a method for evaluating the assembly process capability of the feed mechanism based on Bootstrap was constructed and applied in practice. The results showed that under 95% confidence, the assembly process capability of the feed mechanism of this batch of machine tools was sufficient, and the assembly quality fluctuation was small.