Hot dip galvanizing is the best method for outdoor long-term protection of steel materials. The traditional parameters adjustment and tentatively adding alloy are difficult to meet the requirement of development of modern manufacturing, so comprehensive study of mechanism in hot dip galvanizing is imminent. In view of the large output of hot-dip galvanized steels, the emphasis on the experience and ignoring the theory, the outdated techniques and the serious pollution, the research status and deficiencies of the process theory of batch hot-dip galvanizing in China were comprehensively analyzed based on the coating formation mechanism, the mechanism of alloying coating, and zinc bath liquid characteristics. At the same time, it was pointed out that the interfacial reaction between the matrix and the zinc melt, the adding predictability of zinc alloy elements, the crystallization of zinc on the surface of the workpiece after withdrawing from zinc bath, are very important in the study on mechanism of hot dip galvanizing. It was recommended to improve the mechanism of hot-dip galvanized from the following aspects: the development of the microstructure of zinc coating from the workpiece leaving from zinc bath to the crystallization ending of zinc on the surface of the coating, the application of alloying coating is more important than the mechanism study of alloying coating, to strengthen the research of high-strength low-alloy steel in hot dip galvanizing, to strengthen the research and data accumulation of the surface tension, fluidity and crystallization characteristics of the zinc bath, to study on the pre-design and pre-control of the coating with the combination of the mechanism and the galvanizing parameters.