Omitting viscosity along flow direction, we have simplified the dimensionless Navier-Stokes equations in arbitrary curved coordinate system as the thin layer equations. Using the implicit approximate- factorization algorithm to solve the gas-phase governing equations and the characteristic method to follow the tracks of particles, we then obtained the full coupled numerical method for two-phase, transonic, turbulent flow. The influence of different particle radii, different particle mass fractions and grouped particle size on flow field has been discussed, and the influence of two-dimensional radial particle velocity component and viscosity on specific impulse of rocket motor has been analysed.