The errors in the inertial measurement device include mathematical approximation errors, computer algorithm errors, and initial alignment errors of the inertial navigation system. In many error sources, the approximate errors of the mathematical model of the engineering application can be ignored, and the effects of computer algorithm errors are programmed. In the process, the main error source of the error of the inertial device controlled by the computer program is about 90%. The initial alignment error is mainly caused by the output error of the inertial device.