Urban underground space (UUS) has been playing an important role in the urban development in recent years. The evaluation for its potential becomes essential for urban spatial planning. Previous research emphasized the fundamental data, while this paper not only emphasized the data provided by related departments, but also took into consideration the gap and relation between UUS and urban spatial planning. To provide theoretical support for urban spatial planning, this paper studied a method for evaluating UUS. In this method, an index system for UUS resource evaluation was put forward and its analytical process was based on the Geographic Information System (GIS) and some mathematical tools, such as the analytic hierarchy process (AHP), the most unfavorable grading method (MUGM) and the exclusive method (EM). Then this method was applied to UUS Master Plans and Detailed Regulatory Planning in Chinese cities, and proved to be relatively practicable. The research outcomes are presented in the form of two papers, each with a different focus. Part 1 aims to introduce the evaluation methodology, including construction suitability evaluation & potential value evaluation & volume estimation. Part 2 reports on applications of the method to Chinese cities of Tongren and Changzhou. Part 1 analyzed the concept behind and the process involved in the UUS spatial planning evaluation methodology, combining construction suitability evaluation & potential value evaluation & volume estimation. Based on the factors that influence the development and utilization of a UUS, an index system for UUS resource evaluation is presented. Its primary components are construction suitability (including landform, geology, hydrogeology and the existing construction situation) and potential value (including urban spatial location and land use function). Using AHP, MUGM and EM, the level of each index was quantified and overlaid based on GIS, and then the UUS evaluation output was obtained, such as construction suitability distribution, Resource's comprehensive quality (RCQ) distribution, with manifestation styles of maps and tables. In this research, three models are proposed, including a construction suitability model, a comprehensive quality model and a volume estimation model. The construction suitability model can evaluate the construction difficulty or cost grade, while the comprehensive quality model can evaluate potential benefit grade of every part in the city. They reflect the formula "Quality = Potential - Cost" to some extent. On the other hand, the volume estimation model can calculate the urban indicators for UUS, which can give data support for urban spatial planning.
