Abstract: Based on the relative motion between the pose of cooperated multi-robot end-effectors, the trajectory constraint relation of the cooperative robots is analyzed and a practicable teaching method is proposed. Firstly the method analyzes the kinematic constraint relation between the cooperative robots. According to relative motions between cooperative robot end-effectors, cooperative motion can be divided into two types, coupled motion and superposed motion. Then, the kinematic constraint relation equation of the pose of master-slave robot end-effectors in the Cartesian coordinate system is given in the two motion types. Based on the constraint equation, a trajectory teaching method for multi-robot cooperation system is proposed. Finally, two-robot cooperation system for welding is set up, using which the constraint relation is testified and the teaching method proposed is validated.