Abstract: To improve welding efficiency of piping system, a positioning device of pipe joint was designed for simulating the relative location and direction of two pipe joints in cabins. By analysis of main functions of the device, overall program was proposed, and the entire structure and fixture of pipe joints were designed in detail based on it. According to structural features and functional requirements of the device, coordinate transformation algorithm of forward kinematics was calculated, and inverse kinematics was solved based on it. To test and verify the practical feasibility of the device, two error indicators of overall performance of the device were designed. Based on forward & inverse kinematics and systematic errors of the main moving parts, the Monte Carlo method was used to obtain the probability distribution and overall characteristics of two error indicators. The results showed that the design of the device was feasible.