The important characteristics and influential factors to the annual variation of peek flood in the rivers of Xinjiang Autonomous Region during the later half of20 th century are analyzed according to the annual peek flood series from21representative gauging stations in this region.The research is of significance to the valuation of calculated results for design flood and will promote the research on the flood theory in arid area.Meanwhile more attention will be paid to the importance of long -term observation in gauging station.