The invention belongs to the field of a circuit board cleaning agent, and discloses a water-based environment-friendly cleaning agent for circuit boards. The cleaning agent is prepared from the following raw materials in parts by weight: 1-2 parts of potassium polyoxyethylene lauryl ether phosphate, 1-2 parts of sodium sulfate, 1-2 parts of tetrafluoropropanol, 1-2 parts of sodium citrate, 2-3 parts of benzotriazole, 3-5 parts of isobutanol, 3-5 parts of triethanolamine, 3-5 parts of polyoxyethylene ether, 4-6 parts of diethylene glycol monobutyl ether, 10-15 parts of coco fatty acid diethanol amide and 30-40 parts of de-ionized water. The cleaning agent disclosed by the invention has no problem of stratification, and is good in stability and free from corrosion to metal; and in addition, the cleaning agent is good in compound removal effect.