The work aims to improve surface properties of materials and exploit application of amorphous coating. 304L stainless substrate surface was pre-coated with Fe-Cr-Si-P amorphous alloy powder, and then amorphous coating was prepared by broad-band laser cladding technology. Microstructure and interface characteristics of the coating were analyzed with optical microscope (OM) and scanning electron microscopy (SEM). Flow field model of broad-band laser cladding was established using FLUENT software, and flow field distribution in laser molten pool was simulated. The coating had a typical layered structure. There were planar crystalline and dendrites in the interface zone, large area amorphous zones in the middle and fine equiaxial dendrites on the surface of the coating. Thickness of epitaxial growth dendrites decreased with the increase of laser scanning speed. Flow in the molten pool was mainly convective mechanism. Melt flow velocity was the minimum in the middle of the molten pool, and the maximum on the surface, and reached the peak on the bottom. Distance between the peak value positions and the bottom of molten pool decreased with the increase of scanning speed. The broad-band laser cladded Fe-Cr-Si-P coating is composted of amorphous phase and dendrite crystalline phases, and the coating has a layered structure. The distance between peak value positions in lower part and the bottom of molten pool is decreases with the increase of scanning speed, which approximately coincides with measured distance of the epitaxial growth layer thickness. A model is built for relationship between laser process parameters and thickness of epitaxial growth layer, which provides theoretical basis for controllable preparation of large area amorphous coating by broad-band laser cladding technology.