An integrated ramjet which consists of a liquid fuel ramjet (LFRJ) and solid fuel booster is considered as the best choice of propulsion system for a supersonic, small volume, medium and long range cruise missile. The major components of a liquid ramjet engine are air-intake, combustion chamber and nozzle. Numerical simulation of ramjet engine components in the completely integrated form is extremely useful in cost and time saving when the systems are under design and development. The overall operation of the ramjet engine depends on the individual performance of the air-intake and combustor. Matching of the intake and combustor is essential for the functioning of the overall engine. Many design aspects and associated problems can be addressed by the numerical simulation of individual components of a ramjet engine. However, the proper prediction of a complete engine can be made only by carrying out the simultaneous simulation of all the constituents of a ramjet engine. In the present study the operation of a complete liquid ramjet engine has been numerically simulated and results are presented. The governing equations of mass, momentum, energy and species conservation have been solved to obtain the complete flow field inside a ramjet engine using the FLUENT software.