Abstract: Through collecting and analyzing the historical data, the variation stages, trends, grades and causes of flood disasters in the Baoji region during the period of A.D. 600-2000 were researched. The results showed that flood disasters in the Baoji region may be divided into 4 grades, [WTBX]i.e[WTBZ]. the slight, moderate, serious and extremely serious grades, in which the moderate and serious flood disasters were dominant, and their proportion was 71.55% of the total. Extremely serious flood disasters occurred seldom, and their proportion was 8.94% only. In the past 1 400  years, flood disasters occurred seldom in the 10th, 11th, 12th, 13th, 14th and 15th centuries but frequently in 7th, 8th 9th, 16th, 17th, 18th, 19th 20th centuries. There was a spatial difference in occurring frequency of flood disasters, and the frequency was in an order of Baoji > Fufeng > Qianyang > Fengxiang > Feng County > Long County > Linyou > Qishan > Mei County. The difference of occurring frequency of flood disasters between the highest and lowest values was 26 times. Seasonally, flood disasters occurred mainly in summer and autumn. Flood disasters were jointly affected by the geographical location, precipitation, climatic anomaly undulation and human activities.

Key words: flood disaster, disaster grade, spatiotemporal variation, formation cause, Baoji region