This study introduces a new approach to evaluate the ecological carrying capacity of urban tourism resources (UTRECC), emphasizing the perspectives of “desired” and “undesired”. Based on urban sustainability principles, this study categorizes the load of urban tourism resources into “desired load” and “undesired load”. Using tourism system theory, the study examines the carriers of four key subsystems related to urban tourism resource carrying capacity, including tourism attraction carrier, atmospheric environmental support carrier, waterbody environmental support carrier, and land environmental support carrier. A calculation model for UTRECC is constructed based on 11 carrier indicators and 5 load indicators. This method elucidates the performance of ecological carriers in urban tourism, suggesting that, within certain parameters, a higher carrying capacity index is preferable. Empirical research was conducted in four case cities: Beijing, Shanghai, Chengdu, and Guangzhou. The results reveal significant variations in the tourism resource carrying capacities of these cities, with Beijing and Shanghai exhibiting relatively higher capacities compared to Chengdu and Guangzhou. The findings offer valuable insights for the planning, development, and management of urban tourism, providing a robust framework for future assessments and adjustments of urban resources.