The aim of this study was to develop a GIS/RS based evaluation system for regional ecological security (RES). Wanquan County of Hebei Province was taken as a case study area and 3 types of evaluating indicators, including vegetation changes, LUCC (land use/cover change) and soil erosion, processed by GIS/RS technologies, were selected. By the comprehensive index method, a quantitative evaluation model was built with the three types of indices based on GIS/RS technologies, and their weights were balanced by introducing least squares solution. The final evaluation image and the statistical results were generated in ArcGIS9.0/Spatial Analyst module, so the GIS/RS based model for RES was realized successfully. Through our case study, it was proved that the evaluation study on RES was improved by the intercross between Geoinformatics and Ecology. GIS was a powerful analysis tool, RS was an ideal data-source and GPS could provide the exact real-time positioning information for our study. Just because of the comprehensive application of "3S" technologies, the study on the evaluation of RES was lifted to the positioning, quantitative and visualized level.