The geodesic laser gyroscope is an important tool for measuring the angular velocity of the earth's rotation and provides the basis for the solution of universal time.Environmental changes will affect the geometry of the optical cavity of the geodesic laser gyroscope,which in turn affects the measurement accuracy of the gyroscope.This paper mainly focuses on the error of gyroscope Sagnac frequency difference brought by the tilt of the geodesic laser gyroscope plane.Based on the basic error theory and coordinate system theory,the theoretical model of the influence of tilt on the rotation angular velocity of gyroscope is derived.Allan deviation (AD) method is used to analyze the tilt data from three Laboratories.The raw data is denoised according to the analysis results.Based on this,a tilt error compensation model is developed by using the time series method.It reduces the angular velocity error from tilt by an order of magnitude,bringing the Sagnac output frequency difference closer to the theoretical value.It shows that the noise level of the gyroscope output data can be reduced by constructing a reasonable tilt error compensation model,and it provides a reference for further optimizing the operating environment of the gyroscope and the processing method of related data.