The low-cost attitude estimation algorithm for Sitcom-on-the-Move (SOTM) system is usually complicated,and easily affected by the maneuvering acceleration and the sideslip angle.To solve the problems,we proposed an algorithm based on the spherical simplex transformation Unscented Kalman Filter (UKF),which fused the information from micromechanical gyroscope,accelerator and GPS for estimating the attitude accurately.To improve the real-time performance,the filter used the spherical simplex transformation to reduce the number of sigma points for speeding up the calculation,reducing the computation load and providing better filtering performance.The GPS-measured velocity was used to compensate for the maneuvering acceleration,and the sideslip angle was used to further correct the maneuvering acceleration when the vehicle was turning.Experimental results show that the low-cost attitude estimation algorithm is feasible for attitude stabilization of SOTM in both pitch angle and roll angle with accuracy of ±0.5°.