Abstract: Based on the daily maximum temperature data of Maoming National Meteorological Observatory from 1972 to 2017 and reanalysis data of NCEP / NCAR 2.5°×2.5°, this paper analyzes the characteristics and causes of the change in the number of days of high temperature in Maoming. The results show that there are obvious interannual and decadal changes in the number of high-temperature days in Maoming. The number of high-temperature days has increased significantly since the late 1980s, with periodic changes of 5 a, 13 a, and 23 a. High temperature days are the most in July and the least in May; the duration of the high temperature process is mainly 1 to 2 days and the intensity is weak; the high temperature weather is closely related to the subtropical high; When the west extension ridge point of the subtropical high is westward, the number of high-temperature days in Maoming will be significantly higher. The number of high-temperature days is significantly positively related to the intensity and area index of the subtropical high that year, and significantly negatively related to the ridge point index of the western Pacific subtropical high that year. From the correlation point of view, the area index of the subtropical high had a more significant effect on high temperature.