To meet the needs of the sorting and packaging industries, a new 4-DOF parallel robot mechanism has been presented. The mechanism consists of three main drive branches and one sub-drive branch chain. The three main branches connect the fixed platform and the moving platform, controlling the three translational movement of the moving platform. The sub-drive branch chain is attached to one of the main branches and directly controls the rotation of the end-effector. Therefore, the rotational motion of the mechanism has certain decoupling characteristics. The position equations for the parallel robot mechanism are derived from geometric constraints to analyze the forward and inverse kinematics of the mechanism. The position equations are verified through numerical calculations. The velocity Jacobi matrix of the mechanism is obtained from the position equation, and the kinematic equations are verified numerically by combining the helix trajectory.