The invention discloses a small-scale air quality index prediction method and system for a city, which firstly divides a city area into a plurality of to-be-predicted locations in a grid form; and then acquires historical data related to each model, and based on historical data: establishing corresponding correspondences The current time prediction and the time prediction model predicted at each moment in the future time, establish a spatial prediction model for air quality prediction at the specified coordinates, and establish a dynamic prediction model that characterizes the relationship between traffic data and geographic interest point data and air quality index, an indoor and outdoor prediction model that characterizes the relationship between the indoor air quality index and the outdoor air quality index; when performing the prediction, the established time prediction model, the spatial prediction model, and the dynamic prediction are performed for any real-time moments to be predicted. The model and the indoor and outdoor prediction models are cooperatively trained to fuse the prediction results of all the models, that is, the predicted values of the air quality index at each moment in the respective current and future time periods of each to-be-predicted location.