Two types of 3-RPS parallel mechanisms were proposed, its limb kinematic chain consisted of an arc prismatic pair P, a revolute pair R, and a spherical joint S. The axes of drive pairs of those mechanisms were collinear, parallel, respectively. Mobility, kinematics and transmission efficiency coefficients of these two types of parallel mechanisms were analyzed via screw theory. The rotational center of moving platform of the first parallel mechanism was the center of arc rod, and moving platform rotated around the Zaxis with respect to the other two directions was decoupled. In the second parallel mechanism, the rotational center of moving platform was an intersection point of three straight lines, which passed through each center of arc rod and the center of spherical joint, and this intersection point changed with the posture of the moving platform. In addition, the transmission efficiency coefficient of these two types of parallel mechanisms related to the movement direction of spherical joint of limb kinematic chains.