Six models were built for timely and accurate estimation of PM_2.5 concentration and pollution levels, namely K Nearest Neighbor (KNN) model, BP Neural Network (BPNN) model, Support Vector Machine (SVM) regression model, Gaussian Process Regression (GPR) model, XGBoost model and Random forest(RF) model. Ganzhou City of Jiangxi Province was selected as the study area. The hourly ground-based meteorological data, PM_2.5 concentration data and Merra-2reanalysis data from 2017 to 2018 were used for modelling. The results show that PM_2.5 concentration can also be predicted using visibility and meteorological data when pollutant observation data are missing. In terms of the prediction accuracy of PM_2.5 concentration, the XGBoost model performs best, followed by the RF model, and the GPR model is the worst. The prediction accuracy of the six models was generally highest in winter, followed by autumn and spring, and lowest in summer. Compared with other models, the XGBoost model exhibits a more accurate prediction performance for PM_2.5 pollution level prediction with the comprehensive accuracy rate of 87.6%. Moreover, XGBoost model has the advantages of short training and small memory consumption. Visibility (followed by the relative humidity and time variable) play a key factor in the XGBoost models for PM_2.5 concentration prediction. This study can provide a reference for environmental departments to accurately predict and forecast PM_2.5 concentration.