In order to study the uniaxial tensile mechanical properties of hydroxyl tetrade propellant under wide temperature and confining pressure， the mechanical properties of propellants under different temperatures（-50 ℃， 20 ℃ and 70 ℃）， confining pressures（0.1， 2 MPa and 8 MPa） and tensile rates（100， 1000 mm·min^-1 and 4200 mm·min^-1） experiments were conducted by using a wide-temperature-confining pressure gas test system. The internal microscopic reasons for the development of macroscopic mechanical properties were analyzed by means of scanning electron microscopy （SEM） and micron CT， with the main of revealing the influence mechanism of external load on mechanical properties of high solid content propellants. The results show that the damage of propellant is mainly attribute to“de-wetting” at room temperature and high temperature. At low temperature and atmospheric pressure， the particles suffer the "de-wetting" and ductile fracture. When the confining pressure increasing， it would change to brittle fracture of particles. Nevertheless， the elongation still increases with the increase of confining pressure. Under high confining pressure and different tensile rates， the mechanical properties of the propellant at room temperature and high temperature are similar. Because at this conditions， high temperature weakens the interaction between binder matrix and solid filler， and the “de-wetting” of the propellant are more seriously， but high confining pressure inhibits the “de-wetting” and weakens the influence of temperature. When the time-pressure equivalent superposition principle （TPSP） is used to carry out the fitting analysis of the principal curve of the maximum tensile strength， at low of -50 ℃， the relationship between the time-pressure displacement factor and the corresponding confining pressure does not conform to the standard form， and the superposition principle of TPSP has certain limitations for the use of high solid content propellants.