The Fe75.5C7.0Si3.3B5.5P8.7 amorphous alloy powder is cladded on 304 L stainless substrate by a 5-kW cross flow CO2 laser. The phase, microstructure, thermal stability and microhardness of the coatings are systematically analyzed by optical microscope, X-ray diffractometer (XRD), integrated thermal analyzer and microhardness meter. No crack or void is observed within the coating. The coating has a good metallurgical bond with substrate. The coating mainly consists of amorphous, Fe3P and Fe2Si phases. The microstructure in the near interface region exhibits obvious extensive growth characteristics. A large area of amorphous region is observed in the middle of the coating. The crystallization temperature of the coating begins at 793 K and ends at 835 K. The coating microhardness shows a graded distribution, and the hardest zone is in the middle of the coatings. The highest hardness of the coating is 441.3 HV, which is about 3 times of that of 304 L stainless substrate.