The invention discloses a low-grade heat source driven non-azeotropic mixed working medium combined heat and power system and method. A low-grade heat source input channel is connected with a steam generator through a super heater, and is used for transmitting heat to the working medium side; one end of the steam generator is divided into two paths through a separator; one path is connected with one end of a heat supplying device through the super heater and a turbine in sequence; the turbine is coaxially connected with a power generator, and is used for making saturated steam enter the turbine and expand to do work after being heated through a low-temperature heat source and forming superheated steam so that the power generator can be driven to provide power for a user; the other path isconnected with one end of the heat supplying device sequentially through an evaporator; the heat supplying device is connected with a heat supplying output pipeline, and is used for providing heat forthe user after a saturated solution is mixed with turbine dead steam; and the other end of the heat supplying device is connected with the other end of the steam generator through a booster pump so as to form a working medium side circulation passageway. The low-grade heat source driven non-azeotropic mixed working medium combined heat and power system and method achieve the purpose that power and heat are provided for the user at the same time, and the circulating heat efficiency of the combined heat and power system is far higher than that of a system only used for power supply.