Under the background of climate warming, heat wave events are showing a trend of extending towards spring and autumn. To explore the abnormal signals of atmospheric circulation that cause autumn high temperature and seek theoretical basis for prediction, this paper uses conventional observation data, NCEP/NCAR reanalysis data and other relevant data to analyze the climatic characteristics of the number of high-temperature days in autumn in Jiangxi from 1961 to 2023 and its relationship with atmospheric circulation and sea surface temperature (SST) characteristics. The results showed that: 1) The average number of high temperature days in autumn in Jiangxi is 3.6 days, showing a trend of first decreasing and then increasing. The inter-annual and inter-decadal periods are 4 years and 14 years, respectively. The high temperature intensity mainly ranges from 35℃ to 40℃, with a spatial trend of more in the south and less in the north. The northeast of Jiangxi and the north-central part of southern Jiangxi are high-value centers for high temperature days. The growth rate of high temperature days in southwestern Jiangxi is the fastest. 2) In the years when the high temperature days in autumn in Jiangxi are above the normal, the geopotential height in the Northwest Pacific and the area north of Lake Baikal shows a positive anomaly and the East Asian trough is relatively strong. The Western Pacific subtropical high presents an east-west zonal structure. There is a significant southwest air flow in the lower atmosphere from the North Indian Ocean to the Arabian Peninsula, and the southerly anomaly is proportional to the number of high temperature days in autumn in Jiangxi. Meanwhile, the sea level pressure is lower from the equator to South China, which is favorable for an increase in high temperature days in autumn in Jiangxi. 3) The number of autumn high temperature days in Jiangxi is positively correlated to SST in the North Pacific and the surrounding waters of Equatorial New Guinea Island, but negatively correlated to SST in the Eastern Equatorial Pacific. When the SST in the above-mentioned waters is warmer (colder), it can be influenced by triggering teleconnection wave trains to connect with the Western Pacific subtropical high, South Asia high, and zonal winds over East Asia, thereby affecting the temperature changes in autumn in Jiangxi. Especially, its high correlation coefficient with the North Pacific SST in the previous winter and autumn can serve as a reliable early signal for predicting high temperatures in autumn. This study reveals that subtropical high pressure in the Western Pacific and South Asian high pressure are the main impact systems of Jiangxi''s autumn high temperature. The sea surface temperature in the subtropical areas of the Western Pacific in autumn was significantly positively correlated with the number of high-temperature days.