The Weather Research and Forecasting (WRF) model coupled with the Community Multiscale Air Quality (CMAQ) model was used to simulate the temporal and spatial distribution and the multiscale transport patterns of PM2.5 in 2 large regions (“NORTH” and “SOUTH”), 7 small regions (“North,” “Northeast,” “East,” “Center,” “South,” “Southwest,” and “Northwest”) and 31 provinces in China during January and July of 2015. The simulated PM2.5 concentrations were compared with the observed values to assess the accuracy of WRF-CMAQ. During January and July, local emissions contributed the majority of the PM2.5, with their percentage exceeding 60% in 7 of the regions. External transport was the dominant source of PM2.5 in some of the provinces, such as Shanghai and Qinghai, whereas local emission was the main contributor in others, such as Hebei and Xinjiang. We also identified the primary PM2.5 source in each region, the results of which indicated distinctly different regional transport patterns among the provinces and regions of China.