Abstract: Territorial spatial planning is an important action to implement the functional zone strategy and draw a blueprint for a beautiful country in the future. Evaluations of carrying capacity of resources and environment and developmental suitability of land space are the prerequisite and basis of territorial space planning. Taking Yilong District in the southwest of Guizhou Province as a sample, this article focused on the functional characteristics of ecological improvement, agricultural production and urban construction, chosen a quantitative method as the main method and a qualitative method as supporting method to carry out the evaluations, including single-factor evaluation of resources and environments, integrated evaluation of carrying capacity of resources and environments and evaluation of developmental suitability of land space, and compared with the current land use, the constraints and potential of land space development are identified. The results showed that the area of ecologically important zones accounted for 36.93%, the area of suitable zones for agricultural production accounted for 24.84%, and the area of suitable zones for urban construction accounted for 25.08% in Yilong District. They could be used as key ecological functional zones, main producing zones of agricultural products, and urbanization development zones. The basic farmland area in ecologically important zones was 23.60 km², and the general farmland area was 15.21 km². The basic farmland area in unsuitable zones for agricultural production was 72.17 km², and general farmland was 27.63 km². There was a large overlap in the function directions of the plots. It was recommended to combine the development intentions of the city to clarify the function directions of different regions. The reserve arable land area was 131.87 km², and the reserve construction land area was 114.85 km², which was consistent with the field verification results. This research shows that the parallel evaluation system of karst area can be satisfactorily applied to territorial spatial planning to achieve the regional functional optimization zoning of grid cells.