The real time simulation of the infrared (IR) signature for the naval vessels is studied. Based on the single element method (SEM) and the status space method (SSM), the block is separated into several layers. A simple and convenient calculation method is offered, and the result of the simulation is satisfying. This method is not only helpful to the enhancement of the capability of infrared countermeasure and the subsistence of the naval vassels, but also to the concealment design.