When the measuring distance is selected, it is difficult to balance the accuracy and efficiency. To address this issue, an optimization method of measuring point based on error source for hole shaft straightness detection is proposed. The error source of real part is analyzed. Then, the dimensional error of surface shape of part is obtained. According to the engineering semantics of the error source and straightness tolerance, the simulation function of the surface shape of the part is established. Based on the principle of error theory, the relationship between the measured distance and the error evaluation value is analyzed, which is based on the simulation function. And the point set accuracy function is formulated. For the given tolerance and machining method, a series of simulated surfaces are randomly generated based on the Monte Carlo method simulation principle. By using the precision function of the set of measured points, the best measuring distance of each simulated surface is analyzed and counted. In further, the best measuring distance of real parts is analyzed. Finally, two engineering examples are implemented to evaluate the accuracy and effectiveness of the proposed method. Compared with the theoretical method, results show the number of axial and radial measuring points in the first example is reduced by 1 994 (226) and 42 (396), respectively. The proposed method improves the measuring efficiency under the condition of satisfying the accuracy.