With the consideration of the features of the tri-axial up and down laoding manipulator for numercial control (NC) horizontal lathe, the programmable logical controller (PLC)-based electrical control system with hardware and software is designed. The hardware modules of the control system were included of the PLC as main controller, the touch screen, the servo system, and the power system. The software modules were included of the motion control program, the communication program, and the fault diagnosis program. In order to implement online monitoring the working state of the manipulator, the early fault detection method of the manipulator was given based on the theory of statistic process monitoring by the position feedback of photoelectric encoder signal of the servo motor collected on the manipulator in realtime. The control system of manipulator on NC lathe has early fault detection function, which can improve operation reliability of the manipulator.