Based on the comprehensive strength index of regional high temperature process, the daily maximum temperature of 2452 national stations from January 1961 to August 2017 and the NCEP/NCAR reanalysis data in 2017 were used to analyze the characteristics of regional high temperature process in 2017, as well as the formation mechanism of the second regional high temperature event in summer of 2017. In 2017, regional high temperature event over China showed features of high intensity, long duration, and large coverage. Under the background of climate warming, the maximum influence domain of the single regional high temperature process in China was extending obviously. In the early July of 2017, the powerful continental high pressure controlled the northern part of China, which caused the high temperature event with a wide range of influence and a long duration. In the late July, the vast southern region of China was under the control of the subtropical ridge. The strong downdraft and anti-cyclonic circulation made the atmosphere more stable, which finally led to the formation of high temperature weather.