Enthalpy, transition-state molecules and barrier heights of decomposition reaction of 2-H-heptanuoropropane (C3HF7) were studied with B3LYP/6-31G(d, p) and MP2/6-31G(d, p) methods. Theoretical computation shows that the reaction temperature has obvious effect on the thermal decomposition of C3HF7, and the pyrolysis products include the main product C3F6, a certain amount of C3HF5, CHF3 and (CF3)2C=CF2, and trace concentrations of C2F4, C3F8, C2HF5 and C4F8 at 800℃. The decomposition of C3HF7 into C3F6 is the most important initiation mechanism, with the H transfer reaction to CF3C:CF3 and CF3CF:CF3CF:carbine and F transfer reaction to CF3CH and CF2:radicals, some products including C3HF5, CHF3 and (CF3)2C=CF2 form, and the trace concentrations of C2F4, C3F8, C2HF5 and C4F8 originate from the combination between the radicals of C?F and C?C bond fission and carbine.