Using coating on the hot forming steel can effectively avoid the surface defects such as surface oxidation and decarburization in the thermoforming process, and make the workpiece have a certain degree of corrosion resistance after molding. This paper studies the effect of the variation of microstructure and heat treatment process in the heating process of 22MnB5 hot forming steel with Zn plating layer on coating microstructure and properties. The microstructure and morphology of 22MnB5 with zinc based coatings by different pre-alloying and austenitizing technology are analyzed by SEM, EDS, and glow spectrum analyzer. The results show that under the same pre-alloying time, with the temperature improved, the coating's phases change from ζ phase, δ phase, Γ₁ phase and Γ phase to mainly Γ phase; under the same temperature, as the pre-alloying process time goes by, the contents of Fe gradually increases but Zn decreases, finally the Fe content could reach 88%, and Zn reaches 8% in the coating; the coating is almost all α-Fe (Zn) with only a small amount of Γ phase on the surface, and the thickness of the coating is about 12 μm; high quality coatings could be obtained under the pre-alloying process of heating at 550 ℃ for 30 min and austenitizing at 920 ℃ for 4 min. The result provides important reference for developing new hot forming steel coating.