The drought occurred in autumn， winter and spring in South China from October 2020 to May 2021， especially in Guangdong, where the duration of drought and the degree of precipitation reduction were rare in recent 58 years. Using the daily precipitation and temperature data of 86 national meteorological stations in Guangdong， NCEP/NCAR and NOAA reanalysis data， this paper studies the abnormal characteristics of atmospheric circulation and SST in autumn， winter and spring in Guangdong from 2020 to 2021 by using correlation and synthesis analysis methods， and discusses its relationship with the drought in autumn， winter and spring in Guangdong. The results show that the drought in autumn， winter and spring in Guangdong from 2020 to 2021 occurred under the climate background of less precipitation， and was closely related to the anomalies of atmospheric circulation and SST. In the autumn， winter and spring of 2020-2021， the high-level subtropical westerly jet in the Northern Hemisphere was weakened， the southern section of the Middle East Asia trough was significantly weakened， the ridge line of the Western Pacific subtropical high was significantly northward， the low level south branch trough was weak， the cold air affecting Guangdong was weak， Guangdong is in the water vapor divergence area， and the North Pacific high pressure was significantly enhanced. A La Ni〖AKn~D〗a event with moderate intensity occurred in the equatorial Middle East Pacific from August 2020 to March 2021， the atmosphere responded significantly to the La Ni〖AKn~D〗a event， the Walker circulation strengthened， the upward movement near the Philippines was obvious， and there was a downward movement in Guangdong, so that a cyclonic abnormal circulation formed near the tropical Western Pacific， the South China Sea and the Philippines in the lower troposphere. The cyclonic abnormal circlution blocked the transport of southwest water vapor from the Bay of Bengal and the South China Sea to Guangdong. At the same time， the temperature was significantly higher. At last, the high temperature and less rain led to the occurrence of drought in Guangdong.