According to the characteristics of the fourmode differential laser gyro random error,for the experimental collection of a type of fourmode differential laser gyro static output data,using p order AutoRegressive and q order Moving Average (ARMA(p,q)) model to analyze the testing data. Based on the establishment of ARMA(p,q) model,the fourmode differential laser gyro static output data were filtered by using Kalman filter. Test results show that this method can significantly reduce the random error of fourmode differential laser gyro.