Rate calibration and six position calibration tests are discussed about a kind of micro inertial measurement unit (MIMU). A simple mathematical model of micro gyroscope and accelerometer is designed, some model parameters such as bias, scale factor, cross-axis coupling factors etc are confirmed. The effect of the model compensation is checked by the real tests. The tests result shows that gyroscope drift error compensated is near 0.01 o/s, the accelerometer error is below 10-3 g, the precision of MIMU is highly improved after error compensation, and the mathematical model is simple and the speed of calculation is also high.