Abstract: Two algorithms for prediction of solid propellant rocket motor performance are introduced. Triple Loop Iteration Algorithm is applied to solution of quasi-steady equations（ 5 ）-（ 8 ）. Its computer program comprises a procedure with three iterative loops. Time-Space Alternate Algorithm can be applied to soluting both quasi-steady equations and unsteady equations （22）-（24）. If ρ/t, v/t, p/t in equations （22）-（24） are given, equations （22）-（24） will be reduced to ordinary differential equations. They can be solved by Merson's method. When △ρ/△t, △v/△t, △p/△t are approximated to ρ/t, v/t, p/t, this algorithm for model equationcorresponds to the finite difference schemeIt is an unconditionally stable scheme.A general two-dimensional grain calculation method is introduced for calculation of grain. A comprehensive computer program for above mentioned methods has been written and applied to calculating the performance of three different motors. The results of the numerical examples are consistent with the experimental data.