The invention relates to a pre-driven medium and long term air quality forecasting system and method, and relates to the field of air quality forecasting. The system comprises a meteorological data downloading module, a numerical model driving module and a post-processing module. The meteorological data downloading module is used for downloading reanalysis data 10 days before the report starting time and CFS forecast field data of the report starting time. The numerical model driving module is used for reading an emission list provided by a user, and obtaining a meteorological field review simulation result and an air quality review simulation result 10 days before the report starting time by utilizing the reanalysis data and the emission list. The scheme solves the technical problem of how to carry out pre-driven medium and long term air quality prediction based on CFS medium and long term weather prediction data and improve the prediction precision, and is suitable for air quality prediction.