The invention discloses etching liquor and a circular use method thereof. The etching liquor comprises copper chloride, organic amine, an oxidizing agent, an additive agent and deionized water. In each liter of etching liquor, 10 to 150 g of copper chloride, 10 to 200 g of organic amine, 1 to 100 g of the oxidizing agent, 1 to 100 g of the additive agent and the balance deionized water are included; in the use process of the etching liquor, the solution is alkaline, and the requirement for a device is not high, the use cost is low, operation is safe and environment-friendly, and a detection control system is simple; low etching is achieved, the etching speed is high, and stability is high. A membrane separation technology and a deposition reduction technology are combined, circular recycling of the etching liquor can be well achieved, a product after the reaction is nitrogen and water, other impurities are not brought in, and filter liquor obtained after copper filter and depositing can be recycled to be used for preparing new etching liquor.