The properties of coatings have been analysed theoretically and experimentally throughout the deposition process of SiO antireflection films on facets of 1.3μm InGaAsP/InP laser with semiconductor power amplification.The transmissivities of cavity faces have been increased from 69% and 32.6% without coatings to above 90% and 80% with coatings.The coupling efficiency of device,output power of laser and operating lifetime have been improved.