This paper first designs a new 5-DOF parallel mechanism with 5PUS-UPU for multi-directional 3D printing, and then analyses its DOF by traditional Grubler-Kutzbach and motion spiral theory. It theoretically shows that the mechanism meets the requirement of 5 dimensions of freedoms including three-dimensional movement and two-dimensional rotation. Basing on this, the real mechanism is built, but unfortunately it is found unstable in some positions. Grassmann line geometry method is applied to analyze its unstable problem caused by singular posture, and then an improving method is put forward to solve it. With the improved mechanism, closed loop vector method is employed to establish the inverse position equation of the parallel mechanism, and kinematics analysis is carried out to get the mapping relationships between position, speed and acceleration of moving and fixed platform, Monte Carlo method is used to analyze the workspace of the mechanism, to explore the influencing factors of workspace, and then to get the better workspace. Finally an experiment is designed to verify the mechanism working performance to satisfy the spatial motion requirements of multi-directional 3D printing.