In view of the problem of zero position and sensitivity of inertial device in MIMU are not stable and vary with time slowly, a field fast calibration method based on ellipsoid fitting was proposed in this paper. Parameters like zero position and sensitivity of accelerometers in MIMU were got after establishing ellipsoid constraint model, the program of field calibration was designed and the quadric surface equation was solved: The accuracy and the validity of the calibration method were verified by comparative experiments, the test results show that this field calibration method can be used in the environment without precision calibration equipments (such as shooting range) for field calibration, and the accuracy of this method is equivalent to the calibration results with precise turntable, which is valuable in engineering application.