Abstract: X-ray diffraction (XRD) stress measurement has attracted significant attention because of its non-destructive nature, high accuracy, and broad applicability. However, the optimization and matching mechanisms of its measurement parameters have long lacked systematic investigation. By constructing a multi-parameter coupling analysis strategy, this study systematically reveals for the first time the synergistic effects of key parameters such as diffraction peak position, scanning step size, and number of sin²ψ measurement points on residual stress measurement accuracy. The experimental results show that the selection of the diffraction peak position exhibits a significant angle effect. When the high-angle diffraction peak at 137.282° is used, the stress calculation error is reduced by about 87.64% compared with the conventional angle, which is due to the higher sensitivity of the high-angle 2θ region to changes in interplanar spacing. The optimization of scanning step size is characterized by two-factor constraints. Although the optimal peak fitting goodness (R² > 0.92784) can be obtained with a step size of 0.03°, a balance between measurement efficiency and noise interference must be considered. An innovative minimum data point criterion strategy for the sin²ψ method is established. When the number of sin²ψ measurement points reaches 7, the stress error can be stably controlled within ± 5.7 MPa, providing a theoretical basis for rapid detection. This study breaks through the traditional single-parameter optimization model and proposes a multi-parameter synergistic optimization strategy, offering important theoretical support and a technical paradigm for the X-ray diffraction residual stress measurement.