Using the monthly NCEP/NCAR reanalysis data and the rainfall data from 66 stations in Fujian from 1979 to 2009, this paper analyzes the influences of the variation of Antarctic Oscillation (AAO) in March and April on the rainfall before the flood season (May and June) in Fujian. The results show that there is a positive correlation between the March and April average AAO index and the rainfall before the flood season in Fujian. The stronger AAO index is correlated with more rainfall in May and June, and vice versa. And the positive AAO index anomaly is associated with the positive rainfall anomaly, and vice versa. Furthermore, the analysis of the AAO anomaly found that the significant strong AAO will be corresponding to more active cold air in the Northern China and the stronger wet and warm air in the Southern China. Therefore, the strong frontogenesis will occur in the northern South China, which may result in more rainfall in May and June, and vice versa. These findings may provide a new way to predict the rainfall that occurs before the flood season in Fujian.