According to the topological design method of parallel mechanism based on position and orientation characteristics (POC) equation and the principle of motion decoupling, a three-translation parallel mechanism(PM) with single loop and full motion decoupling was proposed and analyzed. On the basis of this single-loop PM, a third branch chain was added, and then a class of four three-translation (3T) parallel mechanisms with symbolic forward position solutions and partial motion decoupling as well as large working space was designed. Their topological characteristics were analyzed, and the main topological characteristics such as POC, degree of freedom (DOF), coupling degree (κ) and motion decoupling property were obtained. The kinematics and dynamics performance of one of the PMs were analyzed, including the symbolic forward and inverse position solutions according to the principle of kinematic modeling based on topological characteristics. The velocity and acceleration curves were also obtained. Based on the derived Jacobian matrix, the conditions of mechanism singularity were analyzed. According to the deduced inverse position solution formula, the workspace of the PM was analyzed. According to the virtual work principle based on sequence single-open-chains, the dynamic modeling and analysis were carried out to solve the driving force of the PM. The correctness of the dynamic equation was verified by Matlab numerical calculation and ADAMS simulation.The three-translation PMs can be used in industrial space grasping, machining, three-dimensional error compensation and so on.