The invention discloses an environment-friendly water-based cleaning agent which is characterized by comprising the following components in percentage by weight: 15-60% of antirust agent, 5-20% of surfactant, 0.1-0.5% of nonferrous metal corrosion inhibitor, 0-0.5% of bactericide and the balance of water. The environment-friendly water-based cleaning agent disclosed by the invention has the beneficial effects of no toxicity or phosphorus, excellent antirust performance, favorable inter-process antirust effect, wide application range, suitability for cleaning various metals including black metal, aluminum alloy and copper alloy, no corrosion to nonferrous metal, excellent cleaning capability for oil stain with higher viscosity, long service cycle and effective range, simplicity and practicability in use and maintenance, multiple functions for efficiently removing oil, preventing rusting and the like, no harm to body health and no adverse effect on the environment.