Abstract: To simplify the computational procedure and minimize the expensive computer time, the optimum calculation for exit cone contour of nozzle with two-phase flow is carried out by the procedure of two-dimensional two-phase (2D-2-phase) nozzle flow. This procedure consists of computations of both transonic and supersonic two-phase flow. The former provides an exact data at the initial line for the latter.The computation of supersonic two-phase flow is completed by charactristics method. The direct marching method is applied to the interior points and axis points, and the inverse marching method to the wall points. There are seventeen finite difference grids in the flowfield, but the typical grids are only five, the others can be divided into several typical grids.The influences of inertia, compression and rarefaction must be considered in the particle drag and heat transfer formulae for computing the supersonic two-phase flow.The 2D-2-phase specific impulse losses have been computed by the present procedure, and the results illustrate that the optimum initial expansion angles are about 28.5% 29.5°,and 27.0° for parabolic, circular and cubic contours respectively. The 2D-2-phase specific impulse losses of these three nozzle configurations are almost the same when the exit angles are equal and the initial angles are close for the above curves.