Extreme low temperature events often lead to significant impacts on residents" lives and crop growth. Therefore, it is important to analyze the causes of extreme low temperature events. Based on the temperature observation data of CN05.1 and reanalysis data of ERA5 during the period of 1980-2022, this study focuses on the spatial and temporal distribution characteristics of the extreme low temperature event that occurred in the South China in May 2022 and reveals the circulation background and possible factors affecting this event. The analysis reveals that the intensity of this extremely low temperature event is strong, the temperature is lower than 3 standard deviations compared with the average state of May 1980-2022. Besides, the cold lasted as long as 31 days and affected more than 1.5 million square kilometers. Therefore, it was the strongest extreme low temperature event since 1980. Further analysis shows that there was a significant wave train in the middle troposphere over the middle and high latitudes of Eurasia, and also an anomalous low pressure over South China, which made the cold air in the middle and high latitudes move deep south. At the same time, the re-intensified La Ni?a in the equatorial Middle East Pacific made the convective suppression center more westerly and stronger, and the related Rossby wave formed an anomalous anticyclone in the east of the Philippines. Then the southerly wind on the west side of this anticyclone transported warm and humid air from the ocean to South China, converged with the cold air to generate convection which significantly reduced the surface net shortwave radiation and made the temperature lower. Therefore, the extremely low temperature event in South China in May 2022 is the result of the joint action of the circulation related to cold air activity and the Philippine anticyclone. Using these two factors to construct the fitting equation, the reproduced temperature can reach -2 standard deviation.