Abstract: GI-coated hot forming steel has good application prospects, because of cathodic protection and low production cost.However, the problem of'liquid-metal-induced embrittlement(LMIE)'occurs during high temperature deformation of GIcoated hot forming steel.The hot tensile properties of GI-coated hot forming steel at different temperatures and microstructure evolution and cracking behavior of the coating at the corners of U-shaped parts were studied.The forming process window of GI-coated hot forming steel and mechanism of LMIE crack was analyzed.The results provide a reference for the development of GI-coated hot forming steel and the formulation of the hot forming process including heating and forming.