A passive nonlinear error compensation method is proposed for single-frequency laser interferometer. It is realized by changing the location of the wave plate in interferometer to adjust the polarization of the interferometer, which compensates the nonlinear error caused by the non-ideal performance and location of the polarized beam splitter, the depolarized beam splitter, the wave plates and other optical parts. A corresponding integrated interferometer nonlinear error on-line detection system is constructed. The experimental results show that the AC and DC output signal suppression ratio is greater than 500 and the nonlinear quadrate phase shift m is reduced to 0.003 rad (0.15 nm). Through stability measurement experiment in 24 h, m changes within the range of 0.024 rad (1.21 nm), which demonstrates the effectiveness of the method in greatly inhibiting nonlinearity.