The main applications of GPS in forest inventory and surveying are the positioning of sample plot centre and the boundary positioning of sub-compartment. This paper studied the founding of the forest district GPS control network, calculated the conversion parameters of coordinate, then utilized the portable GPS to position the sampling plot centre and subcompartment boundary in forest land. The results indicated that five plots were enough for calculating the conversion parameters of coordinate; and the largest RMS error of single plot positioned by portable GPS was 3.86 m. The average boundary displacement and absolute displacement of sub-compartment’s center were 3.23 m, 3.72 m respectively and the area ac curacies of three sub compartments were higher than 98%. Such a method can meet the requirement of the GPS application in forest inventory and surveying. Moreover, this method is easy and practical and can improve the efficiency of forest inventory and surveying.