Recently, transition metal dichalcogenides (TMDs), represented by MoS₂, have been proven to be a fascinating new class of electrocatalysts in hydrogen evolution reaction (HER). The rich chemical activities, combined with several strategies to regulate its morphologies and electronic properties, make MoS₂ very attractive for understanding the fundamentals of electrocatalysis. In this review, recent developments in using MoS₂ as electrocatalysts for the HER with high activity are presented. The effects of edges on HER activities of MoS₂ are briefly discussed. Then we demonstrate strategies to further enhance the catalytic performance of MoS₂ by improving its conductivity or engineering its structure. Finally, the key challenges to the industrial application of MoS₂ in electrocatalytic hydrogen evolution are also pointed out.