Atmospheric chemical mechanism is one of the most important components to study photochemical processes and develop air quality models. The development and application of several atmospheric chemical mechanisms were summarized. The simplified chemical mechanisms include Carbon Bond Mechanism (CBM), Statewide Air Pollution Research Center mechanism (SAPRC), Regional Acid Deposition Mechanism (RADM), and Regional Atmospheric Chemical Mechanism (RACM) which have been widely used in the past decades and the explicit chemical mechanisms contain Master Chemical Mechanism (MCM) and Common Representative Intermediates (CRI) which were developed rapidly in the past few years. The history, species, and lump styles of these mechanisms were compared. Meanwhile, the research of the evaluation to chemical mechanism by using chamber experiment data and the application of these chemical mechanisms in model development also summarized. Besides, the further demand to the development and improvement of chemical mechanisms was put forward.