Abstract: The partitioning of ⁹⁰Sr and ¹³⁷Cs from high-level liquid waste(HLLW) is one of the important problems for the high-level waste volume reduction and the management of HLLW. The crown ether and calixcrown have the good extracting ability and selectivity to strontium and cesium respectively. Dicyclohexano-18crown-6 (DCH18C-6) and 25, 27-bis(2-propyloxy)calix4-26, 28-crown-6(IPR--C4C-6) were selected as extractants and n-octanol was selected as the common diluent to separate strontium and cesium from high-level liquid waste respectively in INET， Tsinghua University. But DCH18C-6 and IPR-C4C-6 were used respectively in their processes to separate strontium and cesium. The strontium and cesium processes could be simplified if DCH18C-6 and IPR-C4C-6 processes are combined in one process to separate strontium and cesium together. In this paper, the coextraction performance of strontium and cesium from nitric acid medium was studied by DCH18C-6/IPR-C4C-6 and n-octanol as an diluent. Effects of extractant concentration, nitric concentration and temperature etc. on the extraction performance of strontium and cesium were studied. The results show that DCH18C-6 and IPR-C4C-6 in n-octanol has no synergistic extraction ability to strontium and cesium. Strontium and cesium are extracted independently by above two extractants. The extracting and stripping requirements of strontium and cesium can be satisfied by selecting better parameters. 