Based on the data of 64 statistical yearbooks , using the minimum per capita cropland and the model of cropland pressure index , the changes of course and characters of cropland index are analyzed . T he results show that the population continues to increase and the average per capita of cropland continues to decrease from 1949 to 2012 .Cropland pressure index is below the warning line (K<1) before 1998 , and which is ahead of the warning line (K>1) after 1999 . Food safety is safety between 1949 to 1998 . However , the result is reversed between 1999 to 2012 , food safety is in a very insecure , and also continue to an aggravating tendency .%以敦煌市为例，利用1949—2012年敦煌市及甘肃省统计数据，运用最小人均耕地面积方法和耕地压力指数模型，分析敦煌市耕地压力指数变化的特点及其原因。结果表明，64年间，敦煌市人口持续增加，人均耕地面积持续减小；1949—1998年，耕地压力位于警戒线之下，压力低；1999—2012年，耕地压力位于警戒线之上，压力剧增；1949—1998年，粮食处于安全状态；1999—2012年，粮食处于极不安全状态，且有持续恶化的现象。
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