The invention discloses a process and system for treating gasified grey water. According to the process, a power quantity exchange process is provided so as to recover pressure energies contained in high-temperature high-pressure gasified black water, and the pressure energies are converted into mechanical energies so as to carry out external action; after treated grey water is subjected to the combined pressurization of a power quantity exchanger and a centrifugal pump driven by a motor, the grey water is heated by high-pressure flash steam, and then, is conveyed to a gasification section for use; the pressure of the gasified high-pressure black water is reduced to 1.0 MPa after the gasified high-pressure black water passes through the power quantity exchanger, the gasified high-pressure black water is conveyed to be subjected to high-pressure flash treatment, and then, the flash process is not changed; and in order to facilitate the pressure regulation of a high-pressure flash tank and avoid overpressure, a regulation valve is arranged in front of a control valve which leads a high-flash separator to a conversion section, and the high-flash separator is led to a total torch, and the occurrence of environmental incidents, such as torch extinguishment or direct emission and the like, is avoided. According to the process and system for treating the gasified grey water, the process is combined with the system, and the problems of energy source waste, environment pollution, cumbersomeness in operation, and the like, in the prior art can be effectively solved through the improvement on the prior art and the scientific and rational energy utilization.