The present invention relates to an electrolysis rust removing agent, which comprises the following components, by weight, 8-15 wt% of aminosulfonic acid, 1-5 wt% of oxalic acid, 0.7-2.2 wt% of concentrated sulfuric acid, 0.4-1.5 wt% of ferrous sulfate, 0.4-1.5 wt% of sodium chloride, and the balance of water. The electrolysis rust removing agent has characteristics of good electrolysis rust removing effect, high rust removing efficiency, and rapid, stable, safe and durable rust removing process, wherein no volatilization is generated during the rust removing process, no acid mist is generated, no harm is generated to operators, and advantages of environment protection, energy source saving, and cost reducing are provided.