Abstract: The east part of North Agro-pasture Transitional Zone in north China located between the south edge of Inner Mongolia plateau and the Great Wall. It is considered as one of the most sensitive regions of China, for it is in the transitional region among different climatic zones and controlled by the southeast monsoon. The one hand, the area provides human with broad space and huge material production potential，moreover， it plays an important role in the change of regional and global climate and the maintenance of ecological functions; the other hand， the ecological issues of the area are very prominent and ecological environment here is manifold， complex and vulnerable, because of the superposition of topography, climate, vegetation and economic activities in the transitional zone of superposition. Arid climate, water deficit are the main features in the area. The relationship between local people and the environment is very special and important to the locally fragile ecological environment. Some current ecological problems being existed in this area are highly correlated with the historical agricultural development. A climax of reclamation began from Shunzhi (顺治) to Qianlong（乾隆） Period （1644－1795), meanwhile land use patterns in the area also changed. This study area includes 34 cities/counties in the eastern Inner Mongolia, 20 cities/counties in Hebei, 3 counties in northern Beijing, 3 cities/counties in Heilongjiang, 8 cities/counties in Jilin, and 11 cities/counties in the south of Liaoning. In the area, the precipitation is 300-450 mm, and dryness is 1-2; From the southeast to northwest, the terrain gradually transforms from the northeast plains to Inner Mongolia plateau. The land administration information, such as reclamation policy, bumper & poor harvest, reclamation area and so on, are collected from Actual Annals of  the Qing Dynasty（《清实录》）in the periods and are analyzed by the methods of historical literature law and information extraction and classification. Based on the records, the paper analyzes the history of cropland expansion and uses ArcGIS to demonstrate it with spatial distribution maps. The main conclusions are as follows: (1) The cropland continuously increased and accelerated during the 152 years, which was cultivated most in the Qianlong Dynasty. (2) Cropland expansion was mainly brought by northward extension of new croplands and refilling in the existed cropland area. The northern boundary of stable cropland area extended northward from the regions to the south of the Great Wall to the line of Taipusi(太仆寺)-Duolun(多伦)-Chifeng(赤峰)-Weichang(围场)-Aohan(敖汉).  The northern boundary of unstable cropland area went on to the furthest north, reaching the line of Horqin（科尔沁）-Aluhorqin（阿鲁科尔沁） in Yongzheng Period, however, it was more southerly than that of the northern boundary of modern cultivation. (3) People’s spontaneous reclamation was the main reason of the cropland expansion. (4) The northern pastoral area boundary changes express the change of land administration policy under population pressure.  Reclamation policy in the area changed under the four emperors’ reign and generally it tended to acquiesce in refugees’ immigrating.

Key words: east part of North Agro-pasture Transitional Zone, agricultural development process, Qing Dynasty, land administration