The invention discloses a disposable drainage bag which comprises a drainage bag body, a drainage tube arranged at the upper end of the drainage bag body, and a bleeder tube arranged at the lower end of the drainage bag body. A sealing part is arranged on the upper portion of the drainage bag body, reinforcing cloth strips are bound and composited on the two side faces of the sealing part respectively, a reinforcing sealing part is formed by the sealing part and the two layers of reinforcing cloth strips, two inner holes in bilateral symmetry and two outer holes in bilateral symmetry are formed in the reinforcing sealing part, a hanging ring is arranged between the two outer holes, and a binding rope is arranged between the two inner holes. The reinforcing cloth strips are formed by interweaving the warp and the weft, and the warp and the weft are identical in structure, and are each formed by combining and twisting five nylon fibers and three cotton fibers. In this way, the disposable drainage bag is simple and reasonable in structure, can be fixedly bound, and cannot fall off.