Abstract: The empirical orthogonal function (EOF) and correlation analyses are applied to NCEP/NCAR atmospheric circulation data and weather phenomenon data collected at 16 observational stations in Sichuan Basin to study the variation characteristics and caouses of haze in Sichuan Basin in early winter. The results show that on the interannual scale, the haze days in Sichuan Basin in early winter show two different distribution modes, one is the consistent type in the whole region, and the other is the east-west inverse type. The key circulation system affecting the consistent type mode of haze days is that when the number of haze days is more (less), the AO/NAO shows negative (positive) phase, the Southern Eurasian type (SEA) remote correlation wave column shows negative (positive) phase, the Sichuan Basin is controlled by the positive (negative) anomaly of geopotential at 500 hPa, and is affected by the northwestern (southwestern) wind anomaly in the northern (southern) Tibet Plateau, the southwestern warm and humid water vapor transport from the bay of Bengal is weak (strong). The east-west inversion-type circulation system affecting the number of haze days is that when the number of haze days is more in the east and less in the west (less in the east and more in the west), it shows a remote correlation wave train similar to the SEA type. The decrease of precipitation is an important meteorological cause of haze weather in Sichuan Basin in early winter. With the decrease of precipitation, the purifying effect of precipitation on the atmosphere is weakened, resulting in frequent haze weather.