This paper reconsiders the man-land relationship in West Liaohe River Basin through the analysis of settlements' environment and takes the key district of ecologically fragile area, where the improvement of the environment is urgently needed, as the focus of the study. Based on the research of three agricultural reclamation periods in West Liaohe River Basin since Holocene, the paper brought forward that the location of the settlement can be classified as the first choice and the territoriality. Because of the fragile environment in West Liaohe River Basin, there exist not only the environmental differences but also a total different characteristics of the first choice and the territoriality. In the two aspects of height and topography, sloping field of 400-600 m contour is the first choice. It is not only the main immigratory area in each agricultural reclamation period, but also the area with a longer duration of human activity. Region outside 400-600 m contour area belongs to territoriality. Secondary migration is a most important step of compromising the man-land relationship. It is also the beginning of agriculture and planting in territoriality. Moving out of the first choice and moving into the territoriality as the secondary immigration have been through all previous agriculture reclamations in West Liaohe River Basin, which is most prominent during the reign of Emperor Guangxu in the Qing Dynasty. Agricultural reclamation in West Liaohe River Basin was a main process of the environmental change from grassland to farmland. Because of the environment differences between the immigrants' first choice and territoriality, agricultural reclamation in territoriality would bring a more serious disturbance to the environment, thus, this kind of area is not only the focus of environmental issues, but also the key district where the improvement of the environment is urgently needed.