The invention discloses a preparation method for constructing a transition metal sulfide nanosphere electrocatalyst based on a hydrothermal method, and belongs to the technical field of electrocatalytic material synthesis. The transition metal sulfide nanosphere material with excellent electrocatalytic performance is obtained by carrying out hydrothermal reaction on different transition metal salts and different sulfur sources in a mixed solution of water and ethanol according to different proportions. The preparation method comprises the following steps: (1) mixing a metal salt and a sulfur source in a mixed solution of water and ethanol according to a ratio, and conducting stirring until the mixture is uniformly mixed; and (2) transferring the uniformly stirred solution into a reaction kettle, keeping at 180 DEG C for 12 hours, then conducting cooling to room temperature, performing suction filtration, and conducting drying for 2 hours. The obtained catalyst material shows relativelygood electrocatalytic hydrogen evolution performance, and is simple in preparation process, low in cost and suitable for large-scale production.