A numerical model for analysis of thermal and mechanical loads of a rocket motor has been developed. This model of a solid propellant motor corresponds to a short range, fast lunch and cruise type missile. It has been elaborated using the Finite Element Method (FEM) incorporated into commercial Comsol/M code. The experimental data on the thrust profile have been utilised to develop proper initial and boundary conditions for forgoing numerical calculations. The studies have been focused on the temperature and stress evolution within the case and nozzle section of the rocket engine. A special attention has been paid to the graphite insert of the rocket motor throat. The performed analyses proved effectiveness of the modelling methodology that will be applied to investigations of the modified motor performance.