The high performance liquid chromatography ( HPLC) to determine purity of hexanitrohexaaza- isowurtzitane ( HNIW) has been studied in this paper. The method is carried out with ultraviolet spectro- photometer as detector,YWG - C18 column,acetonitrile ( CH₃CN) -water mobile phase. The compared re- sults of calibration curve method,internal standard method,normalization method show that the standard deviation of three methods is all below l% ,the accuracy of normalization method is restricted with condi- tion, the internal standard method is difficult to be accomplished,though its accuracy is higher, the cali- bration curve method is easy to be operated and with higher accuracy. It is prefer to use calibration curve method to analyze purity of HNIW.