To study the effect of mass fraction of hydroxyl-terminated polybutadiene (HTPB) system and temperature on the mechanical properties of paraffin/HTPB fuels, seven kinds of paraffin/HTPB tensile specimens with different formulations were prepared, and the unidirectional tensile experiments were carried out by an universal materials testing machine at a tensile rate of 10 mm·min^-1. The variation law of maximum tensile strength, elongation at break and the initial elasticity modulus of the fuel were analyzed. Results show that the fracture elongation of fuel increases with the increase of mass fraction of HTPB system, while the maximum tensile strength and the initial elasticity modulus decrease. When ambient temperature approachs the melting point of 58 ℃ for paraffin, the maximum tensile strength and initial elasticity modulus of the fuel increase with increasing the mass fraction of HTPB. The maximum tensile strength of fuel increases gradually with decreasing the temperature. In which, when the temperature decreases from 20 ℃ to -40 ℃, the maximum tensile strength of H20 fuel increases from 1.189 MPa to 2.150 MPa. The paraffin /HTPB fuel of HTPB system as matrix and paraffin as filler has mutual block acting force on the interface between its matrix and filler, which can increase the mechanical performance of the fuel.