The invention discloses a workpiece positioning and clamping device, a production line and a production process of a CNC machine tool. The workpiece positioning and clamping device comprises a base, wherein a workbench is arranged on the base, a fixed disk which is used for clamping a workpiece is connected to the workbench, a guide pin which is used for supporting and positioning the workpiece is arranged on the fixed disk, a pressing mechanism is arranged beside the fixed disk, and the workpiece is put on the guide pin and then is pressed downwards by the pressing mechanism, so that the workpiece is processed by a cutter after the workpiece is pressed. By adopting the workpiece positioning and clamping device, the following problems can be solved: (1) because partial positions of the workpiece need to be shaded during spraying in the mode of processing first and then spraying and the shaded positions need to be cleaned at a later stage after spraying, the production efficiency is reduced, and manpower is wasted; (2) because an existing machining fixture needs to make contact with the outer surface of the whole workpiece, outer paint of the workpiece is easy to damage, and the quality problem is generated.