The invention discloses a circulating system of power and refrigeration cogeneration and a method. The system comprises an absorber. The absorber is sequentially connected with a pump, a heat exchanger and a boiler, after being pressurized by the pump, basic working fluid flowing out from the absorber is subjected to heat exchanging by the heat exchanger firstly, and then enters the boiler to be heated; steam after being heated by the boiler enters a turbine to do work through expansion, then a part of working media enters a rectifying tower to be rectified, and remaining working media continue to do work through expansion in the turbine; fluid at the bottom of the boiler enters the absorber to absorb exhausting steam of the turbine and a part of working media at an outlet of an evaporator; fluid at the tower bottom of the rectifying tower enters the absorber, steam obtained by the tower top enters an ejector to serve as working fluid, a part of saturated steam coming out from the evaporator is ejected, and the two streams of fluid are mixed in the ejector; mixed working media at an outlet of the ejector enter a condenser to be condensed to be a saturated solution, and then enter the evaporator to conduct evaporative refrigeration; and another part of saturated steam of the outlet of the evaporator enters the absorber, so that a cyclic process is completed.