The high level liquid waste(HLLW) generated from PUREX reprocessing process contains more than 95% radioactivity of the spent fuel. Among HLLW, minor actinides with long half-life and high toxicity are one of the main factors that need to isolate HLLW from the biosphere for more than 100 000 years in the deep geological repositories. In order to solve the problem of HLLW more safely and reliably, “separation-transmutation” technology has been put forward, that is, the minor actinides and long-lived fission product elements are separated from HLLW by chemical methods, and then the separated elements are utilized or transmuted according to their properties. The effective separation of different kinds of elements from HLLW is the key step in the separation-transmutation technology. The diglycolamide extractants exhibit excellent extractability towards trivalent actinides and lanthanides in HLLW. In particular, the unsymmetric diglycolamides have greater advantage than the corresponding symmetric diglycolamides in relieving or avoiding the formation of the third phase in the extraction process, and at the same time maintain the good extraction performances. In this paper, the development history, synthesis method, extraction performance, coordination mechanism, flow process, and the third phase formation of unsymmetric diglycolamides are reviewed. The extraction ratio, the separation factor and the critical parameters of the third phase formation of lanthanides, actinides and other major fission elements are compared. Some suggestions are provided for the structural design, coordination mechanism research and process application of the unsymmetric diglycolamides.