Ternary bimetallic sulfide silver tetrathiotung-state (Ag2WS4) was prepared by a simple low-temperature precipitation method. The structure of Ag2WS4 was determined using the data from powder X-ray diffraction, which is in space group 1 (4) over bar 2m (I-phase) with a tetragonal unit cell of a = b = 5.950 71 angstrom and c = 9.562 65 angstrom, containing layers of edge-sharing AgS4 and WS4 tetrahedra. The Ag2WS4 was also used as an electrocatalyst for the hydrogen evolution reaction (HER) in acid electrolyte. The results demonstrated that, attributed to its unique composition, large electrochemical active surface area, and high electric conductivity, the Ag2WS4 exhibited superior electrocatalytic activity for HER, in comparison with the ternary counterparts of WS2 and Ag2S with a low onset potential and small Tafel slope. The Ag2WS4 also presented superior stability and maintained the electrocatalytic activity of HER for at least 24 h in 0.5 M H2SO4.