Two kinds of Ni45 B alloy coatings were prepared by high frequency induction cladding in case of different cladding heating time. The microstructure and main ingredient of the coating were observed. The results show that when the heating time increases, mutual diffusion of elements will be increased, so that the buffer layer width increases and the distribution of the various elements in the coating is more uniform. There are a lot of white spots in the coating when the heating time is short , this is due to the aggregation of the chromium elements in the coating. Along with the extension of the heating time, the chromium elements disperse in the coating uniformly and the white spots disappear. The coating with long heating time has a long time in melt state, which make it have enough time to separate the impurity and bubble, so the defects in the coating reduces significantly.