The theoretical investigation on the mechanisms and dynamics of the reaction CHF2OCF2CHFCl+Cl have been studied at the B3LYP/6-311G(d,p),BHandLYP/6-311G(d,p),M06-2X/6-311G(d,p)and further refined by CCSD(T),QCISD(T)methods at the three low levels,respectively.The theoretical reaction Gibbs free energies(△Grθ,298)and reaction Enthalpies(△Hrθ,298)are also calculated at the same levels.The results show that the barrier energy of the reaction CHF2OCF2CHFCl+Cl→CHF2OCF2CFCl+HCl is 6.8kcal/mol,lower than the 10.6 kcal/mol of the CHF2OCF2CHFCl+Cl→CF2OCF2CHFCl+HCl.Calculated total rate constant k=2.90×10-15cm3 molecule-1 s-1 at 296K by means of canonical variational transition state at QCISD(T)//B3LYP/6-311G(d,p)level is in good agreement with the available data(3.2×10-15cm3 molecule-1s-1).In the range of temperature(220-2000 K),the variational effect is almost negligible,and the total rate constant is an positive temperature coefficient.Computational results show that the H-abstraction from-CHFCl group is the major product in the medium and low temperature.The three-parameter expressions(in units of cm3molecule-1s-1)for the title reaction within 220-2000 K is k(T)= 1.38×10-19 T 2.57 exp(-2622.95/T).