Abstract: The designed and experimental process of the teaching and playbalk control system of numerical controlled(NC) welding posi-tioner is narrated.Three teaching devices,teaching-box,joy-stick and computer keyboard were fulfilled with industry control computer and sin-gleehip,and a set of control command system of NC welding positioner was also designed,including program command,track description com-mand and I/O communicating command.The teaching and playback process of NC welding positioner was executed as follows.Firstly.the co-ordinates of all welding positions obtained by teaching devices mentioned above were recorded in the computer.Secondly,relationship and se-.quenee of each teaching point is described by command system.Finally.computer explmned the command and controlled movement of NC weldinl positioner.Using such teaching and playback system,the NC welding po-sitioner could be associated with the welding robot or other auto-weldin equipment,therefore,a flexible welding process upon various metallic components could be realized.The experimental results showed a good effect.