Abstract: The principle and structure of a self-teaching system for arc welding robot isdiscussed in the paper.The system utilizes a proximity/force combined tactile sensoras a robot finger to touch the welding-seams,collects and processes contact-stateinformation with a microcomputer and an intelligent control system,and adjusts thepositions and postures of the finger so as to make them meet the demands of weldinggun in the welding procees.The question of friction is also dealt with,and theresults of sensor calibration and control simulation are expounded.