The effects of returning farmland to forest or grass land w ere investigated with the support of GIS and GPS technology. Some important conclusions can be drawn according to the results from the investigation. A certain number of lands with high soil fertility and small slope degree were reforested in returning farmland to forest or grass land. Such a phenomenon occurred mainly due to dispersed farmlands, distant cultivation locat ions and inconvenient irrigation conditions. The authors suggested that reforestation is a long-term complicated systematic eng-i neering , and should be performed step by step