Xenon, the working medium of satellite electric propulsion system, is easy to enter the supercritical state, and does not follow the ideal gas equation of state in filling and in-orbit application. The error of fluid state and parameter evaluation of xenon is large. In view of this difficulty, the working fluid state test system and test method of xenon were established. The saturation vapor pressure, gas phase PVT and supercritical PVT characteristics of xenon were tested. A new saturation vapor pressure equation of xenon was established. The relative deviation between the saturated vapor pressure test results and the NIST equation is less than 0.2 %. The Helmholtz equation established on the basis of xenon experimental data has a high accuracy, and the deviation from the experimental data is less than 0.5 % within 273 K–358 K. In 358 K–373 K, the deviation from the test data is better than 0.05 %, and the second dimension coefficient is used to prove the accuracy and reliability of the model, which provides a state model for satellite xenon filling and in-orbit application.