Dispersion-corrected density functional theory calculations were implemented to investigate structural characteristics, as well as the hydrogen evolution reaction (HER) capability of 2D 1T' phase MoS2-WS2 van der Waals heterostructures. This work has showed that 2D heterostructures could be of importance in catalysis, particularly in HER. Furthermore, it is showed that building a 2D heterostructure could be a good alternative to the application of strain in improving HER capability of 1T' 2D materials without compromising the adsorption properties of other sites.