Abstract: In the aerospace field, there is a widespread demand for error-proofing and improving the consistency of processing for critical components. Therefore, it is necessary to accurately detect the size and change process of the cutting tool using the in-machine tool setter to improve the in-machine tool measurement accuracy, which is the basis for ensuring tool error-proofing and size wear compensation. This paper investigates the influence of the spatial distributions of positioning and repeatability errors within the machine tool workspace, as well as the tool measurement method, on the measurement errors of a laser tool setter, and establishes the corresponding error model. Further, considering the tool measurement position and measurement feed speed, the corresponding measurement optimization methods are proposed. Finally, the effectiveness of the proposed measurement optimization methods is verified through experiments.