Due to the effect of nonlinear frequency modulation of FMCW laser source, the spectrum of beat frequency appears to be broadened, which reduces spectral resolution, so the nonlinear correction of the light source is a prerequisite for the accurate ranging of this system LIDAR. To avoid the defects of the existing nonlinear correction technology with complex system structure and high measurement cost, a nonlinear correction method of FMCW laser source based on error compensation is proposed in this paper. Through the error between the output signal and the linear regression data, correction data with the opposite trend of change in the output signal frequency is constructed as the modulation signal source of the laser. After several cycles of compensation, the coefficient of determination between the output signal frequency and the linear regression data is gradually improved to more than 0.9995. At last, the effectiveness and feasibility of this method is verified by range measurement experiments.