In order to solve the problems of brittle fracture of liquid metal and high process cost in the hot forming process of zinc-based coated sheet, a new hot stamping process with industrial potential was developed by constructing a hot bath pre-cooling temperature control mechanism, and the reinforcement sheet in the lower section of right A-pillar was produced by HBF1500GI hot bath forming pure galvanized sheet to research the evolution law of temperature field for sheet under the synergistic effect of austenitizing parameters and hot water immersion (above 80 ℃). Then, the metallographic analysis, mechanical testing and scanning electron microscopy were used to characterize the sheet, and the small-batch trial production was carried out on the galvanized sheets with coating surface densities of 65 and 80 g·m-2, respectively. The results show that the new process innovatively stabilizes the forming temperature above the Ms point. The microstructures of parts after process optimization are mainly martensite and a small amount of ferrite, with a tensile strength of 1500 MPa. The stability of 65 g·m-2 galvanized sheet is high and there are very few microcracks,the sizes of all microcracks are less than 10 μm, which proves the feasibility of mass production for hot bath stamping process of galvanized sheet. The process provides a stable, reliable and economical solution for large-scale hot forming of zinc-based coated sheets by precisely controlling the phase transition path.