For the mechanical seal using kerosene as working medium, in order to improve the relative performance, the friction characteristics of seal face need to be researched, for getting the relationships between friction coefficient f and duty parameters G of material pairs. It was started with the mechanical analysis, combined with the fitting calculation of viscositytemperature coefficient for kerosene, and through the frictionwear test between materials,f-G theoretical family curves and test curves were gotten. Besides, contrasting the testing results with theoretical famaly cuves, approximate film thickness in different woring condition are gotten, which provides the reference to the research on using performance of mechanical sealing pairs of low viscosity medium in variable working condition environments.