Abstract: Residual stress will be generated during its preparation, processing and service of silicon carbide single crystal, which destroys its integrity and restricts the excellent performance and reliability of devices. In order to accurately evaluate the crystal quality and improve device performance, research on the measurement of residual stress in single crystal silicon carbide was carried out in this manuscript. Firstly, the relevant theory for solving the residual stress state of single crystal silicon carbide with a hexagonal crystal structure was deduced by improving the original multiple regression analysis method. Secondly, the residual stresses in 6H-SiC single crystal wafer grown along the 10\overline 1 0 orientation was detected by this method. And 214 crystal plane family of silicon carbide single crystal wafer was selected as the measured diffraction plane. Finally, error analysis of the measurement results calculated by applying the data for different numbers of (hkl) reflections was investigated to illustrate the influence of the number of lattice planes on residual stress results. The results indicated that the in-plane stress components of single crystalline 6H-SiC can be determined by multiple regression analysis; the standard deviation was higher than those calculated based on more than five sets of (hkl) crystal planes for stress calculation when given the value of the stress-free lattice spacing d₀. And if the unstressed interplanar spacing was unknown, as the number of crystal planes increases, the error results of plane residual stress gradually decreased. Besides, the error results changed slowly and even tended to steady state when at least six crystal planes were used in the stress calculation. This phenomenon suggests that the experimental residual stress results have high accuracy and high precise. In addition, six or more crystal planes should be selected to solve the residual stress state of silicon carbide single crystal wafer to ensure the reliability of the experimental results.