The problem whether compensating actions(roll, pitch and yaw angle)reach the required standard or not in aeromagnetic survey is of crucial importance in that it affects the compensation coefficient directly.In order to evaluate the magnetic field compensation process, the authors present a method to calculate the pose angle of plane using the rotation relationship between three components of magnetic field measured by three axis fluxgate magnetometer under plane coordinates and the three components of geomagnetic field measured under horizontal coordinates, and to evaluate the compensation action quality.The practicability of the method is demonstrated by applying it to aeromagnetic compensation data(with high precision attitude data)of Panshi area in Jilin, where the results of proposed method is close to that of high precision attitude instrument AIRINS within 1 degree, showing that this method can effectively monitor whether the compensation action reaches the requirements or not during the flight.