Petal-like MoS₂ microspheres were synthesized via the hydrothermal reaction of Na₂MoO₄, CS(NH₂)₂, and H₂C₂O₄. The crystal form and micro morphology of MoS₂ were analyzed by XRD and SEM, and its thermogravimetric and gas precipitation properties were studied via TG–DSC–FTIR. Results indicated that product yield was influenced by the molar ratio of Mo/S, amount of reducing agent, reaction temperature, and reaction time. The crystal form of petal-like MoS₂ microspheres was hexagonal 2H-MoS₂, which petal-like microspheres diameter was about 1-2 μm with 15-20 nm average thickness of petal. The thermal loss process of MoS₂ could roughly be divided into two stages: transformation stage of MoS₂ and phase change stage of MoO₃, wherein, first stage mainly focused in 221.40 °С～603.15 °С, and second stage occurred in the temperature range of 603.15 °С～1220 °С. MoO₂ and MoO₃ were generated in the first stage which thermal loss decreased by 22.30%. A phase change of MoO₃ from solid to liquid and gas appeared in the second stage. FTIR data showed that there was no SO₂ gas at 603.15 °С, which proved MoS₂ completely transformation before 600 °С. Compared with common MoS₂, the petal-like MoS₂ microsphere acted out high reaction activity.