The invention discloses a device and method for converting power as well as refrigerating, heating and generating electricity by the aid of low-temperature heat energy and belongs to the technical field of new energy resources, in particular to a new energy conversion technology. In order to solve problems in the prior art, advantages of a refrigeration cycle technology, a steam generation technology and a vortex tube cold and hot gas diversion technology are combined, low-temperature heat energy in liquid substances of sunshine, air or water and the like is absorbed through low-boiling point working medium to serve as the energy and is converted into mechanical energy and electric energy, refrigeration and heating output is achieved, and dead steam generated from the system is subjected to cold-heat diversion and low-temperature condensation. The device and method has the advantages that pressure and temperature in condensation of the dead steam are effectively reduced, and efficiency of system energy conversion is improved; a pure physical method is adopted with zero release and zero emission, the method is applicable to the technical field of refrigeration of heating-ventilation air conditioning and the like and can provide power for generating sets, vehicles or ships and the like, and heat energy in the liquid medium of sunshine and air as well as water and the like can be conversed and utilized effectively.