A novel four DOF parallel mechanism was designed to solve the problems of complex kinematics analysis, difficult control and small working space caused by the strong coupling of parallel mechanism.The motion characteristics of the mechanism were analyzed by using the spiral theory, and it was known that the mechanism had two rotations and two moving DOF, and could be driven by four moving pairs.The position mathematical model of the mechanism was established, the expression of the inverse position solution was obtained, and the decoupling characteristic of the moving part was analyzed.The velocity of the mechanism was analyzed and the velocity Jacobian matrix was derived.The singular analysis of the mechanism was carried out based on the Jacobian matrix and the singular configuration of the mechanism was obtained.The conditional number index of the mechanism was analyzed, the singular configuration was eliminated by adding redundant driving branches, the conditional number performance of the mechanism was improved, and it was verified that the mechanism had a large working space.