This article was aimed at understanding the relationship between environment, resources and human behavior in an ancient iron smelting site using the Geographic Information System (GIS). The Dazhuangke area, at Yanqing County, Beijing, has four iron smelting sites and several iron deposits that turn out to be a suitable case for the study. According to the significance of environment and resources factors that had impact on smelting activities, the quantitative relationship between the sites distribution and the geographic characters of small area within the scope of the site were established. The study suggests that the sites were strongly dependent on the geographic characteristics such as slope and the height. Most smelting sites were concentrated in the areas with low slope (below 7°) and low altitude (below 650 meters). The relationship between the sites and rivers is close because rivers could provide access to water resources and facilitate other activities. As the development of smelting furnace (i.e., production of iron smelting) grew, a short distance to the iron ore resource was not a high priority choice among small scale iron smelting sites. The results indicate that human production activities depended less on the resources.