The invention discloses a use method of a reinforcement cage seam welder and belongs to the field of manufacturing of reinforcement cages. The use method comprises steps as follows: the sum of main reinforcing bars is set to be A, and the included angle alpha between every two adjacent main reinforcing bars is determined; a plurality of inner-supporting bars are arranged and supported along a first straight line by an inner-supporting bar supporting device of the reinforcement cage seam welder; the main reinforcing bars are fed, specifically, one main reinforcing bar is conveyed to outer sidewalls of a plurality of inner-supporting bars by a main reinforcing bar feeding rack, and meanwhile, the number i of the conveyed main reinforcing bars is equal to i plus one; the main reinforcing bars on the main reinforcing bar feeding rack are welded to the outer side walls of the inner-supporting bars by a welder; an inner-supporting bar rotation driving device drives the inner-supporting barsto rotate; whether welding of the main reinforcing bars is completed is judged, the inner-supporting bar rotation driving device drives the inner-supporting bars to rotate around the first straight line at a constant speed if the answer is positive, meanwhile, a moving bar winding machine moves along a five straight line parallel to the first straight line, and wound bars in the moving bar winding machine are welded to the main reinforcing bars by the welder; manufacturing of a reinforcement cage is completed and if not, the main reinforcing bar feeding step is repeated. With the adoption ofthe reinforcement cage seam welder, the manufacturing efficiency of the reinforcement cages is significantly enhanced.