Liquid cooling technology is an efficient solution to the cooling problem of data centers. In particular, immersion liquid cooling is most ideal and environmentally friendly among the three methods of liquid cooling. The development status of immersion coolant is reviewed, which is the key role of immersion liquid cooling technology, including the technical indicators of ideal immersion coolant, and classification, physical and chemical properties of current immersion coolant. Considering the insulation, heat transfer performance, thermal stability, safety and other factors, it is proposed that perfluoroolefin is an ideal immersion coolant at present. In view of the achievements and existing problems of current research, future research will focus on scientific molecular design of immersion coolants, establishment of efficient and comprehensive screening mechanisms, and development of green synthetic process routes.