In order to solve the problems that multiposition needed to be tested for more and more carriers recently, a low cost and small size system was researched. Based on low precision IMU, taking the information transferred by the primary INS as the measurement, the problem of attitude divergence was modified by kalman filtering arithmetic, and the measure precision of the system was improved, satisfying the operating requirement. Quartz micromachined gyroscope with zero drift of 100 (°)/h and quartz flexure accelerometer with bias stability of 1×10-4g were used as the inertia measure parts, combined with highspeed navigation computer, then a precision less than 0.1° for both pitch angle and roll angle of the system could be obtained through the information of the primarysubsidiary INS. The system was validated in some relative projects and could satisfy the operating requirement.