We report on the performance improvement of long-wave infrared quantum cascade lasers （LWIR QCLs） by studying and optimizing the anti-reflection （AR） optical facet coating. Compared to the Al₂O₃ AR coating， the Y₂O₃ AR coating exhibits higher catastrophic optical mirror damage （COMD） level， and the optical facet coatings of both material systems have no beam steering effect. A 3-mm-long， 9.5-μm-wide buried-heterostructure （BH） LWIR QCL of λ ~ 8.5 μm with Y₂O₃ metallic high-reflection （HR） and AR of ~ 0.2% reflectivity coating demonstrates a maximum pulsed peak power of 2.19 W at 298 K， which is 149% higher than that of the uncoated device. For continuous-wave （CW） operation， by optimizing the reflectivity of the Y₂O₃ AR coating， the maximum output power reaches 0.73 W， which is 91% higher than that of the uncoated device.