Two-dimensional layered structure of Transition Metal Dichalcogenides (TMDs), MoS2 for example, show superior performance of catalysis for hydrogen evolution reaction (HER) as noble-metal free catalysts. However, the active sites of 2H-phased TMDs mainly located at the edge of layered structures, and the basal planes of the materials present inert properties. Therefore, the increase of active sites and improvement of catalytic efficiency for hydrogen evolution reaction by TMDs are of significant importance in the clean energy production. In this study, we identify that the ZT phase of TMDs can be outstanding candidates for HER catalysts by employing density functional theory (DFT), and the phase transition from 2H to ZT can be achieved by mechanical deformations. We obtained the free energy Delta G(H) of ZT phased MoSe2 and WS2 are -0.04 eV and 0.03 eV, respectively, suggesting promising HER activity of the two systems. Moreover, the HER activity is further analyzed by p-band center theory and the hydrogen coverage effect on the HER performance is evaluated as well. This study opens a new window for the application of 2D ZT-phased TMDs and provides a new class of candidates for noble metal-free catalysts for HER. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.