To prepare Fe based amorphous alloys by ultra high speed laser cladding, in this paper, the preset powder coatings with different thickness of 0.4 mm, 0.5 mm and 0.6 mm were prepared by special mold. Next, the coatings were bonded to the substrate with 4% polyvinyl alcohol and dried under the vacuum condition. Then, the orthogonal experiment was designed to analyze the effect of preset thickness, laser power and scanning speed on the single pass cladding width of Fe-Si-B amorphous powder material, also the effect of process parameters on the coating dilution ratio was analyzed by depth of field optical microscope and extremum difference analysis. At last, the microstructure of the coating was analyzed by means of scanning electron microscope (SEM). Results showed that there was a positive correlation between coating width and laser power; the range of coating dilution ratio was 8.8%-12.1%, and the descending order were as follows:preset thickness, laser power and scanning rate. The coating has good metallurgical bonding with the substrate, but there exists crystallization region at the bottom of the coating, which size is 0.5-3.5 μm. Considering the normalization of process factors, the grain size of the coating is greatly affected by the laser energy density, further analysis, the low solidification rate and composition segregation at the bottom of the coating are the important reasons for the crystallization. Compared the result of each process, crystallization degree is the lowest when the preset thickness is 0.6 mm, laser power is 500 W, and scanning feed is 6 000, and it is beneficial to restrain the crystallization when the laser energy density is controlled below 10 W/mm3.