The invention discloses a method of decomposing hydrogen sulfide for preparation of hydrogen and elemental sulfur, which belongs to the technical field of hydrogen production and gas purification. The invention is characterized in that: hydrogen sulfide or gas containing hydrogen sulfide is subjected to ionization through blockage of discharge by using a medium so as to form uniformly distributednon-equilibrium plasma, and hydrogen sulfide spontaneously decomposes into hydrogen and elemental sulfur in the plasma; when there is a photocatalyst in the plasma, energy in the photons of the photocatalyst can be utilized to promote decomposition of hydrogen sulfide, and complete conversion can be realized under proper conditions. All the frequently used solid photocatalysts can be used in the above mentioned process, e.g., titanium oxide, cerium oxide, zirconia, zinc oxide, cadmium oxide, copper oxide, molybdena, tungsten oxide, zinc sulfide, cadmium sulfide, copper sulfide, molybdenum sulfide, tungsten sulfide and a mixture composed of two or more selected from the above-mentioned photocatalysts; the photocatalysts can also be loaded on a porous material to prepare load type catalysts. The method provided in the invention is especially applicable to treatment of gas containing hydrogen sulfide in the industries of natural gas, petroleum and coal chemistry and is also applicable topreparation of hydrogen and elemental sulfur through dissociation of gas containing hydrogen sulfide in the fields of metallurgy, sea and the like. The method has no special requirements for or restriction on the source and composition of gas; thus, the method has universality to preparation of hydrogen through decomposition of hydrogen sulfide.