Since the high precision inertial sensor is very expensive, the application and dissemination of the inertial navigation system have been limited to a certain extent.For this reason,a structure and scheme of a low cost micro inertial measurement unit (MIMU)/Encoder integrated precision attitude heading reference system suitable for the practical applications of some radar vehicles has been proposed in this work. The mathematic models of the initial alignment and the integrated attitude heading reference system have established.The initial heading alignment was carried out by receiving the north seeking results of the flexible gyroscope north seeker. By considering the working mode, the two velocity error observed quantities and the three position error observed quantities of Kalman filter were 0 after deducting the lever arm effect.The information fusion of the strapdown inertial navigation resolution and the data of the heading encoder was carried out by the Kalman filtering,thus the optimal estimation of the carrier navigation parameters has been obtained.A practical prototype has been designed and fabricated, and has been tested in laboratory and in the user′s working site. The results showed that the pitch precision and the roll precision of the prototype was equal to or less than 0.015° and 0.015° respectively in the static state; the pitch precision and the roll precision of the prototype was equal to or less than 0.025° (1σ) and 0.025° (1σ) respectively in the dynamic state.