Abstract:"Double evaluation", the abbreviation of the evaluation of resource and environmental carrying capacity and territorial development suitability, is the important basis and prerequisite for the implementation of spatial planning. This study systematically expounded the scientific concept, study framework, and research process of "double evaluation", and discussed the core role in promoting the high-quality development of spatial development. This article firstly depicts the main development of "double evaluation" in MFOZ researches, including the proposal and improvement of the theoretical concept, the establishment of evaluation framework, and the application in MFOZ planning. Then, we analyze the main function of "double evaluation" and its irreplaceable fundamental role in optimizing spatial development pattern. As an effective means of cognizing land surface, "double evaluation" could provide the comprehensive and scientific understanding of regional background conditions as well as recognizing the prominent problems and major contradictions in spatial development. Based on it, the "double evaluation" would support basic materials for spatial planning compilation and guiding spatial planning implications by coupling various types of planning in different levels and supervising the implementation of planning. The limitations and proposals of the "double evaluation" are discussed to proper use it in actual work, which emphasizes that the adjustment of technical methods with local conditions and other basic work should also be taken into account. Meanwhile, we discussed the main features and problems of "Guidelines for the Evaluation of Resource and Environmental Carrying Capacity and Territorial Development Suitability (Trial)", which was recently released by the Ministry of Natural Resources. Lastly, suggestions are made on the direction of improving and deepening the method and application of "double evaluation" in the optimization of spatial development pattern.