In order to predict the service life of propellant exactly, data change of mechanical properties was used to estimate ageing failure of propellant. Adopting the method of heat-accelerated ageing test, the relationship between the mechanical properties including impact strength, compression strength and compressibility and ageing time and temperature were studied. Results show that the decline of mechanical properties of polymer materials caused by ageing, decay will not influence the safety service of RB nitramine propellant, and the service life of RB nitramine propellant exceeds its safety storage life obviously.