In order to study the mechanical properties and failure mechanism of solid propellant under extreme low temperature environment, the uniaxial tensile test of a three-component butyl hydroxyl propellant was carried out under different temperatures, wide range of superimposed pressure values and high strain rate conditions by adopting the self-developed wide-temperature-superimposed pressure loading test system and the electron microscope scanning observation of fracture morphology, which analyses the effects of temperature, tensile rate and superimposed pressure values on the mechanical properties of propellant and discusses the damage and destruction mechanism of propellant under different working conditions. The effect of temperature, tensile rate and peripheral pressure value on the mechanical properties of propellant was analysed, and the damage mechanism of propellant under different working conditions was discussed. The results show that when the tensile rate increases, the superimposed pressure increases and the temperature decreases, the elongation of the "dewetting" point of the propellant decreases, the "dewetting" point moves forward, and "dewetting" occurs inside the propellant. There are superimposed pressure and strain rate thresholds, above which the propellant is more prone to "dewetting" behaviour. At low temperature, the maximum elongation of the propellant is more sensitive to changes in high tensile rate, but it has good mechanical properties, its maximum tensile strength and maximum elongation with the increase in superimposed pressure and the trend of increasing; the propellant damage damage form with the decrease in temperature and the increase in tensile rate, the performance of the "dewetting" damage, matrix fracture and particle cracking three damage modes combined.