Abstract: This paper focuses on welding robot on-line teaching. Operator (welder)can pull the welding torch at the end of the robot and process welding openition freely, while the robot is in the state of zero-force controlling.After the robot have taken the records of the teaching track and the welding parameters,the robot can replay the welding process according to the above recorded parameters precisely.It is of momentous practical significance to reduce teaching period and increase welding quality.