Using digital satellite remote sensing TM data, the monitoring of cultivated land changes in the region of Yellow River mouth were carried out by methods of classification results overlay and land use map supported visual change detection. Indices of cultivated land change as well as its related natural and human-related factors were derived from TM data. Correspondent natural environment factors and human influences were analyzed accordingly. Results show that obvious change in cultivated land occurred in Kenli County, which decreased by (5 321.8) hm~2 from 1987 to 1998, i.e. 483.8 hm~2 every year. These changes indicated the aggravation of soil salinization, and the influence of adverse human activities. The countermeasures of ecological environment security of the study area were proposed.