A type of 3—PTT CNC serial-parallel manipulator with 5-DOF was designed based on comprehensive analysis of the advantages of serial and parallel which characteristics for complex surface processing. The configuration and degrees of freedom was analyzed by using decomposition and synthesis. The analysis and calculations show that the 3—PTT manipulator can satisfy the design needs of CNC serial-parallel machine and the configuration is reasonable. The working space and posture limit of manipulator was analyzed based on the singular constraints and posture factors in Matlab. Simulation results show that the analysis can reflect the complete working space of 3—PTT CNC serial-parallel machine tools and provide a theoretical basis for automatic control of working process.