Through the collection,reorganization and analysis to the historical data and materials,the time and grade of the drought and flood disasters has been compiled for Ankang City.In addition,we tried to correlate the natural disasters with the location,migration,and reconstruction of Ankang City in the history.The results showed that,from 500BC to 2000AD,drought disasters altogether occurred 79 times during these 2 500 years,averagely one time per 31.65 year,while flood disasters occurred 140 times,approximately one time per 17.86 year.During 500BC to 1000AD,the natural disasters were rarely recorded,and more were found since 1000AD.The highest frequency of the recorded natural disasters was found during the period from 1400AD to 2000AD.The extreme flood disaster was the reason for the migration of Ankang City from the old city to a new site for twice.However,the return of Ankang City back to its old site was a synthetically action effected by many factors,such as water transportation,farming and cultural psychology of the residents.