Abstract: A study on distributed feedback quantum cascade lasers（DFB-QCLs） with rear facet high-reflectivity（HR） coated has been presented.Compared the DFB-QCLs with and without facets HR coating,the threshold current density was reduced by 20% and the optical output peak power was increased by 50% and the slope efficiency was increased by 44% at room temperature.From the comparison of the threshold current densities of DFB-QCLs with and without HR coated,the waveguide loss of the laser is about 7.25 cm^-1.