Abstract: he early American settlers believed that wilderness areas were useless landforms that contain evil elements, and therefore should be conquered and exploited. This attitude towards wilderness used to be the mainstream trend of ideology in that age. As the expansion of the frontier ended at the end of the 19th century, an increase in environmental degradation occurred as an unexpected result. This issue alerted a group of pioneers taking a new interest in environmental protection activities, calling for wilderness preservation. It became a transition point for change in attitude towards wilderness lands from conquering to preserving in the United States. Learning from a substantial amount of real life practices done at the beginning stage, the U.S. Congress passed the Wilderness Act in 1964, which set up the National Wilderness Preservation System(NWPS) and gave the designated wilderness areas the highest form of protection of any federal land. In over 50 years, the NWPS gradually expanded and now about 5% of the area in United States is designated as wilderness areas. At the same time, the quality of the wilderness management was also improved. The establishment and development of the NWPS is a revolutionary step for the American Protected Areas System, which effectively protected the natural processes and multiple values of the American wilderness areas.