Most studies of temporal and spatial distribution characteristics for droughts and oods analysis were conducted only from the perspective of a single factor (precipitation), while ignoring the impact of the characteristics of the underlying surface on the formation of droughts and oods. Using the daily precipitation data of 88 meteorological stations in Hainan province from 1970 to 2019, the 30m resolution DEM data and land use dataset, etc, the precipitation Z index is used to evaluate the drought and ood levels in Hainan. The analysis results were revised by underlying surface data to evaluate the spatiotemporal characteristics of the drought and ood area in Hainan. The drought-prone areas and ood prone areas in Hainan Island were divided, and on this basis, the set pair analysis method was used to identify the regions with alternating drought and ood areas in Hainan. The results show that the overall arid area shows an obvious downward trend, while the ood area presents an increasing trend.The drought-prone areas throughout the year are more concentrated in the northeast of Hainan Island, while ood prone areas are mainly distributed in the eastern coastal areas. The regions where drought and ood occur alternately are small but concentrated. The drought and ood prone areas and alternate drought and ood areas before and after the revision by the underlying surface were compared. It can be seen that the overall trend is relatively similar and obvious before and after the revision. The result of drought areas before revision is 7.97 times larger than that after revision. The ood prone areas before revision are 2.91 times larger than that after revision. Finally, combining climate and underlying surface factors, suggestions for drought and ood prevention are put forward.