The invention provides a galvanization online deironing process utilizing hydrogen peroxide and whitewash. The process includes the following steps that a plating auxiliary soaking a steel pipe conveyed from a dilute acid pool and a solution composed of the hydrogen peroxide and the whitewash are subjected to a thorough mixing reaction in a deironing pipeline, and a mixed solution A is obtained; the mixed solution A obtained after the reaction is directly introduced into a plating auxiliary buffer tank, Fe(OH)3 precipitates out in the plating auxiliary buffer tank, and a mixed solution B withflocculent precipitates is formed; and the mixed solution B in the plating auxiliary buffer tank is filter-pressed, Fe(OH)3 is removed, and the filtered solution returns to a plating supporting grooveand can continue to be recycled. The utilization rate of zinc is increased, as a treatment system is totally closed in the pipeline, volatilization of potassium chlorate and ammonium hydroxide is reduced, the utilization rate of agents is greatly increased, heat losses of the plating auxiliary are reduced, the emission of waste is reduced, and a large amount of raw material cost is reduced.