To generate the simulated image of an infrared target accurately and realistically, the effects of an infrared sensor need to be simulated accurately. Sampling and blur effects are the typical main effects of infrared sensors. First, the mathematical models of sampling and blur effects are discussed. Then, both effects are taken into account at the same time. Their algorithms are combined into one algorithm by a ray tracing method and a new mathematical model is proposed. According to the established model, the simulation image under the co-action of sampling and blur effects is obtained. The experimental results show that the established model can reflect the degradation of images due to sampling and blur effects. This is helpful to the improvement of calculation accuracy and efficiency and the increase of the fidelity of infrared image simulation.