The invention discloses a multi-phase permeameter and a rock permeability determination method. The multi-phase permeameter comprises an injection system, a cooling system, a model system, a metering system, an automatic control system, a pressure return system, a vacuum pumping system and a data acquisition and processing system, wherein the injection system is used for injecting carbon dioxide and liquid; the cooling system, the automatic control system, the pressure return system, the vacuum pumping system and the model system are used for simulating formation conditions; and the metering system and the data acquiring and processing system are used for date statistic measurement. The method comprises experiments of vacuum pumping, core saturation and displacement, wherein injection rate and injection pressure are changed by an injection pump, so that parameters required for the permeation experiment can be acquired, and salt precipitation capacity generated by desiccation effect can be measured. According to the invention, the operation is simple, automatic control, acquisition and handling by using a computer are realized, and limitations and defects of conventional experimental apparatuses and methods can be overcome.