The utility model relates to a drain system of a small-sized submersible pump or a submersible sewage pump. The drain system solves the currently existing problems that drain pipes frequently fall off, connection positions leak, water backflow easily happens inside pipelines when water is discontinuously pumped and the like. The measure for solving the problems includes that the novel submersible pump drain system mainly comprises a pump outlet pipe (1) and a drain pipe (2); a joint pipe (3) and a rapid joint (4) are sequentially connected between the pump outlet pipe (1) and the drain pipe (2); a stop plate (5) is connected between the pump outlet pipe (1) and the joint pipe (3); and the rapid joint (4) is connected with the drain pipe (2). The drain system is simple and rapid in connection; the drain pipe is not easy to fall off; connection positions have no leakage; and the drain system solves the problem of pipeline water backflow when in discontinuous water pumping, and improves the working efficiency of a pump.