The liquid metal magneto-hydro-dynamic (LMMHD) system is a promising power generation converter for a variety of heat sources. This paper presents a novel concept of the self evaporating-driving LMMHD system, in which the liquid metal is driven by the vapor from its own evaporation. It has advantages of safety, higher electrical conductivity, a simplified structure without mixer and separator, and therefore a more reliable and higher efficiency. First, the basic principles of this system Were introduced, in comparison with that of a conventional LMMHD System. Second, simulations were conducted to study the physical process of the evaporation of liquid metal in the heater and the characteristics of vapor liquid flow in the following tube. Finally, three main impacting factors, namely inlet velocity, inlet temperature of liquid sodium, and temperature of the pipe wall, were discussed, respectively: The findings verify the feasibility of the proposed self-evaporating-driving LMMHD system and present the outlook for future research.