Abstract: Because of the flammability and explosibility of hydrogen，CSNS hydrogen circulation vacuum system design should not only satisfy the vacuum performance requirements，but also take a series of hydrogen safety measures，namely hydrogen safety design method，so as to ensure the safe operation of the vacuum system.First，briefly introduce the principle of hydrogen circulation system of China Spallation Neutron Source and compose of hydrogen circulation vacuum system.Then，according to the risk characteristics of hydrogen and related knowledge of hydrogen safety，starting from hydrogen safety design point of view，introduces zone definition of an explosive atmosphere the safety design method of vacuum system.