For achieve welding torch trajectory continuous smooth and welding time the shortest, which of the underwater visual welding robot end, a method of interpolation the location-time discrete points of each joint based on the five b-spline curve was proposed. The start-stop continuous are been smooth for welding by this method, then the sequential quadratic programming filter trust region method was used to optimize the time by the constraint condition of kinematics of robot, so the efficiency of welding work was improved. at last, the simulation experiment showed that trajectory continuous smooth of the each joint for the vision robot, meanwhile welding was used less time to accomplished, and the property of motive controlling and trajectory tracking were improved for the welding robot.