The reasons of the high-frequency signals and noise signals generated from the Moire fringe optolectric signal and the relative method of self-adaptive filtering were discussed,in order to improve the quality of Moire fringe optoelectric signals of the incremental optoelectric encoder，decrease the impact of high-order harmonic frequency in the main count signal and increase the SNR for the stable output of sinusoidal waveform.The window function of the grating pair from both macro and micro perspectives,and the uncertain reasons of the Moire fringe optoelectric signal waveform were analyzed.The original fundamental frequency signal was retained by applying a method of self-adaptive filtering which can filter out high frequency signals.Meanwhile,the adaptive filtering process was derived and proved from the perspective of mathematical model of self-adaptive filtering,and its adaptability was discussed.In order to complete the effectiveness analysis of the self-adaptive filtering,several key indicators and their effects needed to be focused in the design of the self-adaptive filtering encoder.The effect of the adaptive filtering was equivalent to a narrowband band pass filter whose center frequency was the fundamental frequency,and the pass band would change with the random variation of the fundamental frequency.Thus,the relevant self-adaptive filtering could filter out all the high frequency component signals in the count signal except the fundamental frequency signals，and amplify the addition white gaussian noise in the circuit to make the output waveform of the moirefringe optoelectric signal approach the standard sinusoidal wave.The experiment results show that distortion degree of the Moire fringe photoelectric signal is reduced by 8 times.