Abstract: The atmospheric chemical mechanism is a key component of the air quality numerical model (AQNM), and is an important mean and method for investigating the atmospheric chemical processes. The development of the three simplified chemical mechanisms including the carbon bond mechanism (CBM), the regional atmospheric chemical mechanism (RACM), and the Statewide Air Pollution Research Center mechanism (SAPRC) which are widely used in AQNM were summarized. The comparison of the lump styles, the chemical species and the reactions, as well as the updates and the applications in AQNM of the different chemical mechanisms were presented. The comparisons of the simulation results of the AQNM by using different chemical mechanisms in previous studies were analyzed and summarized, and the reasons of the difference caused by the different chemical mechanisms used in the AQNM discussed. Additionally, the suggestion of the selection and application of the chemical mechanisms in AQNM research was proposed.