Aiming to improve the current situation of the simulator fidelity evaluation system, a new theoretical framework based on fuzzy logic and fuzzy set theory is introduced to quantitatively evaluate the simulation fidelity of infrared camera simulators. This framework is an objective and multiparameter evaluation system, which is related to many fields such as fuzzy logic, curve similarity evaluation, image quality assessment, and information theory, etc. Compared with those available, a multiscale fidelity evaluation analysis, which includes performance characteristic evaluation of the total system and image quality assessment of the camera outputs, is considered more compromisingly in this evaluation system. Consequently, the new framework here has better task flexibility and it is easier to quantify and compare the fidelity results between different camera simulators with the same or similar mission requirements.