Abstract: Gyro is served as an important inertial device for vehicle attitude measurement. The error drift of gyroscope is due to long transportation and storage，which leads to the reduction in the measurement accuracy of motion parameters， thus needing to calibrate the gyroscope before use. A non-turntable field-calibration method for medium accuracy gyroscope based on optimal analysis is proposed in accordance with the working conditions without high precision turntable equipment in the field and the requirement of the indexes of medium accuracy gyroscope. The calibration problem is transformed into an optimal analytical problem by establishing the mapping relationship between the gyro output and the earth rotation rate as well as the accelerometer output. The method， combined with the improved genetic algorithm， is used to achieve the goal of simplifying the operation steps， doing not rely on turntable and other auxiliary equipment， shortening the calibration time and improving the calibration accuracy. The validity of the method is verified by mathematical and hardware-in-the-loop simulation experiments. The results show that the method can be used effectively to achieve the accuracy of medium-accuracy gyroscope calibration. Key

Key words: gyroscope, fieldcalibration, turntable, optimalanalysis, improvedgeneticalgorithm