Abstract: A flexible manufacturing system of non root chipping double-sided arc welding robots is studied in order to realize robot automatic welding for thick plate of low alloy high tensile steel.Master-slave coordinated method is adopted.Motoman robot is master and KUKA robot is slave.According to the ending position attitude of welding torch of master hand,reference path plane of plate is look on as symmetric plane.Motion path of slave-hand is deduced by kinematics coordinate conversion.And Master-slave coordinated motion of double-sided arc welding robots is reached and is verified by coordinated motion experiment.