Abstract: In this study，a new quantitative assessment index（DI）was constructed, which took CI index and the ratio of precipitation and water demand on developmental stage as its parameters by using the data of five typical stations in the spring corn growing areas in Gansu province. Drought index level was graded based on the relationship between it and the meteorological yield from 1985 to 2007. Using linear correlation test and an example application analysis method, the feasibility of indicator was relatedly validated. The results showed that the change ranges of DI index during the whole growing season at Jingyuan and Yongchang stations were the smallest from 1985 to 2007 and their DI index values were the lowest too. The next was Yuzhong station, and change ranges of DI index during the whole growing season at Xifeng and Wudu were the largest, and their values were the highest. The fluctuations of DI index during jointing-silking stage at Xifeng and Wudu stations were very obvious，and their values were the biggest too, while the fluctuations of DI index during jointing-silking stage at Jingyuan and Yuzhong were very small，and their values were the lowest too. The assessment results were consistent with the actual situation of the areas under study. In conclusion,compared with the drought index of previous general ones,DI index data were relatively easy to obtain and simple to calculate.The indicator not only contained the meteorological significance, but also increased the biological significance. The indicator could be used to study drought disaster damage assessment for specific crops from various regions.

Key words: Gansu province, Spring corn, Drought, Assessment index