In this work, investigation of the thermo-structural response of steel-composite rocket nozzle is carried out using the finite element method; in the form of commercial package ANSYS. A validation of ANSYS for thermal and structural analysis is done first for simple problems, then the analysis done with the nozzle. The result of thermal analysis shows that thermal loads have a great effect in generating a huge amount of stresses on the nozzle structure (more than 60% from the total stresses on the nozzle). The convictive heat transfer coefficient has a great effect on the temperature transferred to the nozzle wall. The composite material resists temperature augmentation, so it is regarded as a thermal protection material.