The invention provides a simple steam generating device comprising a conventional steam generator and a generator as well as a steam scuttlebutt, a cyclic water tank, a steam diversion controller and a hydroturbine. The steam scuttlebutt is in a vertical tubular shape, is provided with an end enclosure at the upper port and an open lower port, the end enclosure at the upper port is connected to the steam generator through a steam pipe, the lower port is inserted in water of the cyclic water tank; the hydroturbine of an axial flow type is arranged in the vertical tubular steam scuttlebutt and is higher than the water surface of the cyclic water tank, the vertically arranged hydroturbine shaft horizontally penetrates through the wall of the steam scuttlebutt through a transmission mechanism to be connected with the generator; steam produced by the steam generator is conveyed to the steam scuttlebutt under the control of the steam diversion controller to cause the water attack of the steam, lead the water of the cyclic water tank to enter the steam scuttlebutt from bottom to top and be pushed out by the steam from top to bottom, the downstream water pushes the hydroturbine, and the hydroturbine drives the generator to generate electricity.