A mass of optical components existing in reference interferometer of frequency-sweeping interferometry system can bring nonlinear error.According to the nonideal splitting capability of polarizing beam-splitters,the generation principle of nonlinear error was analyzed in this paper,and the function of nonlinear error was given,and the improved method to eliminate nonlinear error is proposed.The paper simulates the real frequency-sweeping interferometry system with MATLAB.The result shows that nonlinear erro...