The invention relates to a treatment process of a carrier of a device which is used to directly change chemical energy to electrical energy, in particular to a plating solution for tumble-plating and a tumble-plating method of a steel battery shell. The plating solution comprises the following components in parts by weight: 80-120 or 200-350 parts of main salt, 30-100 parts of anode activator, 3-60 parts of buffering agent, 20-30 or 180-250 parts of complexant, 0.5-2.5 parts of stress reducer, 0.005-0.1 part of main brightener and 0.3-1.0 part of auxiliary agent and is prepared by dissolving the components in water. The tumble-plating method of the invention comprises the following steps in turn: degreasing, tumble-plating and bleaching, wherein during tumble-plating, the pH value of the plating solution is 4.0-4.6 or 6.5-8.5, the temperature is 40-70 DEG C, the current density is 0.2-3A / dm<2>, the rotational speed of the drum is 4-12rpm, and the tumble-plating time is 180-300 minutes. The coating of the invention has write and bright appearance, high luminance brightness and powerful corrosion resistance.