The invention provides an environment-friendly high-efficiency water-based circuit board cleaning agent and a method for preparing the same. The raw material formulation of the cleaning agent comprises a surfactant, a corrosion-retarding active agent, a chelating agent, a defoamer, a cleaning solvent and water. The preparation method comprises the following steps: accurately weighing various raw materials according to the ratio of the formulation, adding the raw materials into a reactor to be stirred evenly, and keeping the mixture stand to obtain the cleaning agent of the invention. The cleaning agent has the advantages of scientific and reasonable raw materials, simple and practicable preparation method, nontoxic and non-corrosive product, no inflammable and explosive properties, non pollution to the environment, high cleaning cleanliness and low cost, is biodegradable, can be cleaned through both immersion and ultrasonic, and has significant economic benefits.