Aiming at the problem of initial alignment of the laser gyroscope single-axial rotation inertial navigation system, the error parameters of the inertial device affecting the alignment accuracy are analyzed, the effect of gyroscope installation error on the alignment accuracy and accelerometer bias estimation is analyzed and the simulation is carried out.The simulation result indicates that the gyroscope installation error can bring alignment error and accelerometer bias error. The alignment accuracy can be improved through calibrating accurately the gyroscope installation error angles.