The invention provides a system for calibrating an inertial platform system gyroscope torquer coefficient. The inertial platform system is placed on a placing pedestal, power is on till work is normal, and rotation of a platform body is carried out, so that a calibrated gyroscope is in a vertical position; a platform body horizontal axis is accurately locked and controlled according to a horizontal direction frame angle; start time of a positive direction torque applied to the gyroscope and a negative torque applied to the direction gyroscope is recorded, and stop time of a positive direction torque applied to the gyroscope and a negative torque applied to the direction gyroscope is recorded. The coefficient is obtained by calculating vertical direction framework angle sensor pole pairs. The calibrating method reduces requirements on unlevelness of the platform system placing pedestal, and improves calibrating precision of the torquer coefficient.