Based on collecting,sorting and analyzing on historical document records in Jinghe River basin from 1 644 to 2003,grades,temporal and spatial variation characteristics and causes of flood disasters during the period are studied.At the same time,the flood characteristics in that period are also analyzed combined with the flood deposition profile in the lower reach of Jinghe River.Results show that the total times of disasters in Jinghe River Basin from 1 644 to 2003 are up to 1 65 ,an average of once every 2.1 8 years.These flood disasters include more moderate and big flood disasters,less mild and catastrophic ones.It is shown that flood disasters in Jinghe River basin had been increasing from 1 644 to 2003,with the highest flood frequency during 1 894-1 953 and the lowest during 1 644-1 723.According to the spatial variation characteristic of Jinghe River basin,flood frequency is the highest in the upper reach and the lowest in the middle reach.Flood disasters happened in the upper,middle and lower reachs at the same time are generally 4-grade catastrophic flood disaster.The cold,warm,dried,moist changes of different climatic stages and destructive vegetations by human activities are main causes for the occur-rence of flood disasters in the basin.Flood disasters in the period of 1 644 -2003 made the floodplain deposition profile of 2.56 m thick in the lower reaches of the Jinghe River.The deposition layers of this profile mainly pro-duced by catastrophic floods,part of big and moderate floods.Flood frequencies recorded by this profile are signifi-cantly less than the historical document records.%通过对泾河流域1644－2003年洪涝灾害历史文献资料的搜集、整理和分析，对该时期泾河流域洪涝灾害等级、洪涝灾害时空变化特征及其成因进行研究。同时结合泾河下游洪水沉积剖面，对该时期洪水特征进行分析。研究表明：泾河流域1644－2003年发生洪涝灾害总计165次，平均每2.18年发生一次。主要以中度涝灾为主，其次为大涝灾，轻度涝灾和特大涝灾发生次数较少。1644－2003年，泾河流域的洪涝灾害总体呈现不断增加的特点，泾河流域洪涝灾害发生频次最高的是在1894－1953年，发生频次最低的是在1644－1723年。泾河流域发生的165次洪涝灾害中，上游发生的洪涝灾害最多，其次为下游，中游最少，上、中、下游同时发生的洪涝灾害为4级特大涝灾。不同阶段气候的冷暖干湿变化和人类活动对泾河流域植被的破坏是泾河流域发生洪涝灾害的主要原因。1644－2003年的洪涝灾害在泾河下游形成了2.56 m厚的河漫滩洪水沉积剖面，该剖面沉积层主要由特大涝灾、部分大涝灾和中度涝灾形成，剖面记录的洪水频次比历史文献记录的洪水频次要明显少。
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