Abstract: Redevelopment approach of underused urban land has played an important role in the regional urbanization and the sustainable development of undeveloped areas, in order to improve efficiency of land use. To implement the redevelopment strategy, it is necessary to identify the specific boundaries of underused urban land for different types of land use. Taking the central urban area of Yushe County, a provincial poverty-stricken county in Shanxi Province, as a study area, this study has collected the field data, including shantytown transformations, industrial and commercial revenues, land use intensity, building structures, infrastructure situation, and environment qualities. The original data was processed in ArcGIS software to build a basic geodatabase. Firstly, two types of parameters can be divided for underused urban land using system theory, including internal and external affecting factors, based on the features of regional development and differences of land use. Three evaluation systems of indicators were developed for commercial, industrial, and residential land. Each evaluation indicator system mainly included eight dimensions: building structure, spatial layout, land use intensity, land output benefits, geographical environment conditions, location conditions, surrounding infrastructure conditions, and ecological environment effects. Secondly, a combination matrix evaluation model considering internal and external factors was established to identify underused urban land, particularly when a land block has the low efficiency level for internal or external evaluation in the combination matrix, according to the relationship between the part and the whole. Finally, a recommendation was made for the redevelopment directions of underused urban land, based on various features of underused commercial, industrial, and residential land. The results showed that: 1) The internal and external index grade of commercial land was relatively uniform, whereas that of industrial land was concentrated in the low level. There were differences in the internal and external index grade of residential land, in which the external index was mainly low-grade, while the internal index grade was characterized by uniform distribution of low-grade and high-grade. 2) In the amount and area of underused urban land, two blocks of commercial underused land were identified accounting for 0.43% of the total underused urban land, and two blocks of industrial underused land were identified accounting for 9.51%, as well twenty-one blocks of residential underused land were identified accounting for 90.06%. It infers that the residential land mainly contributed to the underused urban land in underdeveloped counties. 3) In the spatial distributions of underused urban land, there were obvious spatial features in residential underused land, mainly distributed in the edge of town and the central areas. In the commercial and industrial underused land, there was scattered pattern without typical spatial characters. 4) The level of underused urban land in Yushe County mainly included 11, 12, 14, 21 and 31, according to the internal-external evaluation. A modified redevelopment strategy was proposed for different functional zoning and specific types, base on the heterogeneity of land use and the features of spatial distribution. The findings can provide a sound reference for the identification of underused urban land in underdeveloped counties.