The invention relates to the field of plasma chemistry, and discloses a low temperature plasma system for decomposing hydrogen sulfide, and a method for decomposing hydrogen sulfide. The system comprises a gas supply-gas distribution unit, a plasma reaction unit and a product separation unit, wherein the gas supply-gas distribution unit, the plasma reaction unit and the product separation unit aresequentially connected through pipelines, the plasma reaction unit comprises a low temperature plasma reactor and a plasma power source, the reactor comprises an inner cylinder, an outer cylinder, acenter electrode arranged in the inner cylinder, a barrier medium and a grounding electrode, the barrier medium is arranged around the side wall of the inner cylinder or wraps the outer surface of thecenter electrode or forms the side wall of the inner cylinder, and a ratio (L1:L2) of the thickness L1 of a discharge gas gap to the length L2 of a discharge region is 1:(0.5-6000). According to thepresent invention, with the apparatus and the method, the hydrogen sulfide conversion rate can be increased.