The invention discloses a resistance spot welding technology for improving quality of welding spots of dual-phase steel. The resistance spot welding technology comprises the steps that firstly, the flatness of the to-be-welded dual-phase steel is adjusted to be 1 mm / m or below through pressurization; then, a spot welding machine is connected with a current to preheat the to-be-welded dual-phase steel; after preheating, the welding current is adjusted, and the to-be-welded dual-phase steel is subjected to heating welding; and the welding current is cut off, spot-welded joints quickly cool and form molten cores, and after the molten cores cool to the martensitic structure transformation temperature or below, a temper current is connected, and postwelding temper heat treatment is carried out. According to the resistance spot welding technology for the dual-phase steel provided by the invention, before welding, the flatness of the to-be-welded dual-phase steel is adjusted, spot welding is carried out through the manner of preheating-heating-cooling crystallization-tempering, and the problems that liquid metal in the molten state splashes and affects the welding quality and possibly causes unintentional harm to human bodies during the welding process are avoided; and besides, the welding spots are relatively stable during the welding process, the welding deformation is reduced, a brittle structure is changed, the quality of the welding spots is improved, the welding spots are prevented from having shrinking holes and cracks, and the quality of a product is improved.