Abstract: The system error equations in the SINS transverse coordinate method are deduced for the transverse coordinate system. According to the solutions from the static base system error equations, the impact of system initial errors and inertial measuring unit errors on the transverse coordinate method is analyzed. System errors are simulated, and compared with system errors from the geographic coordinate computation method. Theoretical analysis and simulation results show transverse velocity errors and horizontal attitude errors are a type of periodic oscillation;position errors, azimuth error angle, wander azimuth error and heading errors increase with time. The transverse coordinate method can solve the problems arising when system errors increase and calculations output singular values in the geographic latitude and longitude coordinate calculating method.