The invention discloses an environmental-friendly trash can capable of automatically filtering waste water. The environmental-friendly trash can comprises a trash can body. An inner barrel is put on the inner bottom of the trash can body, and the bottom of the inner barrel is of a funnel-shaped structure. One end of a water outlet pipe extends into the inner barrel. The lower end, located outsidethe trash can body, of the water outlet pipe is in threaded connected with a connection sleeve. The lower end of the connection sleeve is fixedly provided with a filtering cylinder. The filtering cylinder is internally and sequentially provided with a silver sand layer, a biochemical cotton layer and an activated carbon layer from top to bottom. The bottom of the filtering cylinder is in threadedconnection with a protection cover. The two sides of the inner top of the protection cover are symmetrically and fixedly provided with abutting rods. The upper ends of the two abutting rods abut against the two sides of the bottom of the activated carbon layer. The lower portion of the interior of the inner barrel is fixedly provided with an annular fixing rod in the circumferential direction, thetop of the annular fixing rod is fixedly provided with a filtering net through screws. One side of the top of the trash can body is provided with a sealing cover in a hinged manner. The environmental-friendly trash can is novel in structure, ingenious in design, reasonable in structure and suitable for popularization.