The NCEP reanalysis data and observational data are exploited to reveal the characteristics of the Western Pacific Subtropical High (WPSH) and its influence on the persistent heat wave that affected a vast area of southern China in the summer of 2013. The hot spell was mainly and directly caused by the influence of anomalies in the WPSH. In the present study, the features of the westward extension and northward shift of the WPSH and its persistency are studied; the anomalous atmospheric circulations over the mid- to high latitudes and over the tropics are also investigated. In particular, the influence of tropical circulation systems, such as the cross-equator flows, Intertropical Convergence Zone, and typhoon activities, are further examined. Results of the present study are helpful for better understanding of the formation of persistent heat waves in southern China.