The invention is suitable for the technical field of production of stainless steel, and provides a lightweight oxidization, annealing and acid washing method for cold-rolled strip steel of 304 austenitic stainless steel. The method comprises an annealing step, an alkali electrolysis step and a mixed acid washing step, wherein the strip steel in an annealing section is heated by open fire lower than 850 DEG C; the excess oxygen concentration is within 8-11%; the strip steel is heated by the electromagnetic induction higher than 850 DEG C, and is heated to 1120 DEG C; and scale and a poor chromium layer on the surface of the strip steel are removed by the alkali electrolysis and the mixed acid washing after the annealing. Compared with the prior art, the scale generation quantity on the surface of the strip steel can be obviously reduced in the annealing process; the acid washing section can improve the electrolysis and acid washing efficiency; the electricity consumption is reduced; the mixed acid washing time is saved; the length of the acid washing section is shortened; the equipment investment and the equipment space are saved; the waste liquid and waste gas emission can be reduced; and the environmental pollution is relieved.