In this paper, thermal decomposition process of molybdenum concentrate in vacuum was thermodynamically analyzed, and decomposition mechanism of Mo-S system in molybdenum was mainly studied. To further investigate and analyze the electronic properties in different temperature, the simulation calculations of MoS2(0 01) surface and Mo2S3(0 01) surface density of states, electron density difference, electronic orbital and Mulliken overlap population were carried out by density functional theory(DFT) formalism. The dynamics simulations results of MoS2(0 0 1) surface and Mo2S3(0 0 1) surface were obtained the temperature range of phase transforming are 1573 K-1673 K and from 1473 K to 1573 K at 20Pa, respectively. The interaction of MoS2 and Mo2S3 shows that thermal -decomposition of MoS2 and Mo2S3 does react, when new SS bonds and Mo-Mo bond are formed instead of Mo-S bond fracture. The experimental results of the thermal decomposition of MoS2 and Mo2S3 were in accordance with the thermodynamics theoretical calculation results and ab-initio molecular dynamics simulation results. (C) 2017 Elsevier Ltd. All rights reserved.