Abstract: The on-line programming of MAG welding parameters is a novel method of intelligent controlling of welding quality which aims at improving welding robots adaptive ability.The author established an on-line programming system of MAG welding parameters for arc welding robot with vision.On-line programming of MAG welding parameters experiments have been carried out, which are based on FUZZY math model focusing on the controlling of the weld penetration.The gap and root face of weld and the welding time are used as input variables,while welding current and welding speed are used as output variables.The experimental results prove that the above system is reliable and uniform penetration is obtained.