Weatherindexed insurance is a new type of weather indexbased products for transferring risk. Compared with the traditional agricultural insurance, this new product has obvious advantages on reducing moral hazard, adverse selection suppress and management costs reduction and so on. But there are also obvious defects such as basis risk. In order to reduce basis risk, this paper selects Anhui winter wheat as the object, and uses moving average method, precipitation anomaly percentage method, and multiple regression analysis to investigate the relationship between droughts/floods and winter wheat yield loss in each municipality of Anhui. The results show that P values of drought and floods are both high in some areas, and in most wheat producing areas, P values of floods is less than P values of drought. The results indicate that drought/flood index insurance is not applicable in all areas, and yield of winter wheat is affected more severely by floods than drought.