The invention discloses a microemulsion liquid membrane chemical applicable to treating heavy metal, ammonia nitrogen and radioactive wastewater. The microemulsion liquid membrane chemical comprises a membrane phase and an internal water phase, the membrane phase is mainly composed of an organic solvent, a support film agent, a carrier substance and water, and the volume ratio between the membrane phase and the internal water phase is 1:(0.5-2). A method for treating waste water by the microemulsion liquid membrane chemical includes the following steps of firstly using the membrane phase and the internal water phase to prepare a W / O type emulsion, then adding the W / O type emulsion in an extract tower to perform a waste water treatment, transferring a mixed liquor obtained from the treatment to a liquid separating tower to perform still standing and layering, subjecting layered oil phase to a subsequent high pressure electrostatic emulsion breaking, releasing pollutants from an emulsion dispersed phase to form an organic phase and a pollutant containing solution, recycling the organic phase, and subjecting the pollutant containing solution to a recovery processing. The microemulsion liquid membrane chemical and the treating method thereof applicable to treating heavy metal, ammonia nitrogen and radioactive wastewater have the advantages that the equipment investment is small, the land occupation is small, processing capabilities are high, the cost is low, the secondary pollution is absent, the fluidized processing and all-way automatic control can be achieved, and the like.