In this paper, a comparative study has been carried out of gas reactor type Small Long-Life Gas Cooled Fast Reactor in some associated designs as its one of the candidates generation IV reactors that are expected to start operating in 2030. The comparative study has been done with study focuses on the role of the reactor in economics, safety systems, reactor waste management and proliferation resistance. The results of the study showed it has highly prospects for the operation because of their role in supporting economic growth and transport systems, passive safety systems based on natural circulation, the replacement cycle fuel with a long interval of time, the waste management related to some fuels candidates its use and resistance to nuclear proliferation.