A method based on hydrophilic interaction chromatography (HILIC) coupled with mass spectrometry (MS) was developed for determination of hydroxyethyl hydrazine nitrate (HEHN). The effects of the composition of mobile phase and parameters for MS detection were investigated on the optimization of chromatography separation, time required for analysis, and detection sensitivity. Good linearity is obtained under the concentration range of 0.01-0.1 μg·mL^-1 with R²=0.9991, and the limit of detection of 1.2 ng·mL^-1. Recovery of two HEHN samples with concentration of 0.0250 and 0.0900 μg·mL^-1 is determined as 98.1% and 97.7%, respectively, while relative standard deviation (RSD) is no more than 1.6%, indicating good precision of the method. A real sample of liquid propellant is determined by this method, and the content of HEHN measured as 12.5%±0.3% is in accordance with the prepared concentration of 12.9%.