The invention provides stripping liquid for aluminum alloy and a stripping method of the stripping liquid. The stripping liquid comprises sodium hydroxide, sodium metaaluminate, triethanolamine, ammonium chloride, sodium thiosulfate, sodium bicarbonate, ammonium sulfate, ammonium molybdate and copper sulfate, the content of the sodium hydroxide is 50g / L-75g / L, the content of the sodium metaaluminate is 5g / L-20g / L, the content of the triethanolamine is 30 ml / L-45 ml / L, the content of the ammonium chloride is 15 g / L-30 g / L, the content of the sodium thiosulfate is 15 g / L-30 g / L, the content of the sodium bicarbonate is 10 g / L-25 g / L, the content of the ammonium sulfate is 5 g / L-15 g / L, and the content of the ammonium molybdate is 3 g / L-10 g / L. The formula of the stripping liquid is adjusted, the triethanolamine, the sodium thiosulfate, the ammonium sulfate, the ammonium molybdate and the copper sulfate are added in the new formula and are used as active negative ions and inhibitors, reaction rate is controlled, the corroded degree of aluminum is reduced, and the quality of reworked products and rework utilization rate are improved.