A theoretical model of the temperature field and infrared radiation field is presented,the physical characteristic of which is the separate treatment of the three wavelength regions of the radiation of the sun,the sea and atmosphere background,and the target,and based on the model the complete set of equations of the temperature field and radiation field for the ship in question are obtained that are then used to developed a computer software to obtain the field distribution and to simulate the thermal images of the target.The flow chart of the software is presented and key points concerning the programming are discussed.The numerical results and the simulated graphs for the infrared images of a ship are calculated using the software.The results are compared with the real infrared images of the ship and the main features of the two results are in good agreement.