“Remote sensing mechanism modeling is the foundation for understanding the laws of nature and the prerequisite for quantitative remote sensing inversion. China has established a relatively complete Earth observation system and launched a series of domestically produced remote sensing satellites. How to fully utilize the application efficiency of domestic satellites and serve the national economic construction has put forward an urgent need for the development of high-precision remote sensing mechanism models. The directional models of bidirectional reflection and thermal infrared radiation are two important mechanism models in optical remote sensing. The model scenarios have evolved from homogeneous surfaces to complex surfaces, covering leaves, soil, canopy, and complex surfaces composed of fragmented land types and complex terrain. The paper summarizes the main progress of current optical remote sensing mechanism models from component scale, canopy scale, and complex surface scale. Component scale models include leaf and soil models, canopy scale models include continuous vegetation, discrete vegetation, and row structure vegetation models, and complex surface scale models include mixed and mountainous models of different land types. A multi-scale optical remote sensing mechanism model system has been formed, consisting of leaves, soil, canopy, and complex terrain, which can explain the basic laws of bidirectional reflection and directional thermal infrared radiation in multi-scale scenes. The optical remote sensing mechanism model is the key to supporting quantitative remote sensing applications, playing an important role in the effective evaluation of optical payloads, improvement of observation techniques, inversion of surface parameters, and simulation of land surface models. The article concludes with a prospect for the future development of optical remote sensing mechanism models. This paper introduces the research progress of optical remote sensing mechanism models in multi-scale scenarios, and establishes a multi-scale optical remote sensing mechanism model system of leaves soil canopy complex surface, providing a solution for quantitative remote sensing applications.”