In order to study the relationship between horizontal attitude error angle and horizontal gravity disturbance of SINS (strapdown inertial navigation system) on moving base, the transfer function between horizontal attitude error and horizontal gravity disturbance on SINS mechanization was deduced in uniform linear motion in North-South direction and East-West direction. The distribution of zero and pole of transfer function was analyzed. In addition, the transfer function between horizontal attitude error angle and horizontal gravity disturbance was analyzed in integrated navigation mode. The amplitude-frequency characteristics of transfer function on SINS mechanization and integrated navigation mode were analyzed by simulation. Compared with the SINS mechanization, the cut-off frequency of integrated navigation mode was higher, and the attitude error angle of inertial navigation was affected by high-frequency gravity disturbance signals more obviously. Therefore, the INS needs higher resolution gravity disturbance data to compensate the gravity disturbance in the integrated navigation mode. However, there is a limit for the resolution of gravity disturbance used to compensate for the high-precision inertial navigation system. Too fine gravity disturbance data will only bring cost for measurement and storage instead of improving the attitude accuracy of the inertial navigation system.