Computational model on burning rate change of composite propellant under tensile strain was established, and experimental verification was done on the model. The results show that the model corresponds with experimental data within tensile strain increasing from 0 to 20%. Burning rate ratio and tensile strain obey the quadratic relationship, burning rate increases with strain; Burning rate ratio of composite propellant which has lower poisson ratio increases faster as tensile strain decreasing; The less binder component of composite propellants, the more significant the burning ratio changes under strain state. Loose and crack will appear on the binder under tension, and interstices appear between the binder and AP. The exposed area of AP increases, furthermore the propellant burning is faster, and the burning ratio is bigger. ©, 2014, Journal of Solid Rocket Technology. All right reserved.