Abstract: Observation-based model (OBM) is one of the most widely used tools for analyzing atmospheric chemical processes, and it has broad application prospects in the in-depth analysis of observational data and comprehensive understanding of regional complex air pollution. To promote the application of OBM in atmospheric chemistry studies and to promote coordinated prevention and control of PM_2.5 and O₃ effectively and scientifically, the development history of OBM structures and its built-in atmospheric chemical mechanisms, and the application of OBM in identification of formation regimes of O₃ and secondary aerosols as well as the chemistry of other important trace gases were summarized. The results demonstrated that the upgrading of the OBM structures and atmospheric chemical mechanisms prompted the application of OBM to be a powerful tool for comprehensive analyses of atmospheric chemical processes rather than just identifying O₃ formation regimes. Therefore, OBM has played an important role in the prevention and control of regional complex air pollution in China due to its enhanced applicability. However, the limitations of OBM structures, the lack of core technologies for OBM, and limited observational data restricted the further application and promotion of OBM in atmospheric studies in China. The following suggestions are put forward for solving these issues: choose appropriate numeric models for application and take full advantages of OBM in practical applications; develop online systems for running OBM and localized atmospheric chemical mechanisms with China's independent intellectual property rights; establish representative regional monitoring networks to provide comprehensive data for OBM applications.