The governing equations are the compressible full Navier-stokes equations. Maccormack's time-dependent explicit scheme is used to solve axisynmetric internal flowfield of the solid propellant rocket motor. A turbulent model based on the Bald-win-lomax algebraic scheme is employed to get the coefficient of turbulent viscosity. The solution of the internal flowfield for the soliel rocket motor with tube grain is obtained. The results are satisfactory. The methods are of reference value to the engineering design of SRM.