Abstract: During the sub-rapid solidification process, the interfacial heat transfer between the substrate and melt has a direct effect on solidification process, structure morphology and surface quality of the solidified shells, and the transient interfacial heat transfer is the key point. The research progress of transient interfacial heat transfer at home and abroad is reviewed from three aspects including the research methods, the influence factors of transient interfacial heat flux and the influence of the heat flux on solidification microstructure. The problems in the current research work and the research direction in future are pointed out.