The invention relates to a slight chromatic aberration welding technology for a spheroidal graphite iron casting, which is used for treating defects of the casting. The slight chromatic aberration welding technology mainly comprises the following steps of treating a base material, preparing a groove, preheating the base material, performing welding, performing stress relief annealing, performing chromatic aberration inspection and checking the hardness. According to the method, the welding preheating temperature and the annealing temperature are controlled, so that the heat affected zone is reduced, the hardness of a welded joint is lowered, and the welding chromatic aberration is reduced; therefore, after being welded, the casting can reach a color, a thinner heat affected zone, reasonable hardness and a qualified metallographic structure which are close to those of the base material.