The invention relates to an asymmetric control method of a non-secondary commutated direct current resistance welder, in particular to the asymmetric control method which is applied to various control devices of welders with resistance-typed points, convex and seams; the power is supplied to the two ends of a primary coil of a welding transformer in chopping pulse waveform; a forced demagnetization pulse is applied in the opposite direction of the chopping pulse for supplying the power after the inputting of a plurality of chopping pulses so as to eliminate or reduce residual magnet generated by single-direction power supplying of the welding transformer; the invention solves that the release of the stored energy in the welding transformer is carried out in the natural state when the chopping voltage input is zero and when the two groups of chopping pulses are inputted; enough stop time exists necessarily between the two groups of chopping pulses, or the energy stored in short time can not be released completely; the energy output of the welding transformer is improved by applying the forced demagnetization pulse, thus being beneficial to the welding of color metals such as aluminium, titanium, and the like, and being beneficial to the improvement of the control precision of the welding time.