The invention discloses a three-stage injection type refrigeration system. The three-stage injection type refrigeration system comprises a condenser; the output end of the condenser is divided into three routes, one route is connected with the second stage injector, another route is connected with a pump, and the third route is sequentially connected with a throttle valve, an evaporator and the first stage injector; the output of a generator is divided into two routes, one route is connected with the first stage injector, the other route is connected with the third stage injector; and both the first stage injector and the third stage injector are connected with the second stage injector. The three-stage injection type refrigeration system has an energy-saving effect, effectively reduces the quantity of working gas required by the injectors, reduces the quantity of heat required by the generator, increases the entrainment ratio, reduces the volume of the injectors, increases the energy efficiency by about 5%, and achieves a greater pressure ratio. The three-stage injection type refrigeration system is simple in configuration, low in manufacturing cost, and compact in structure.