The urban ecosystem carrying capacity (UECC) represents the sustaining function of urban ecological supporting system (UESS) on urban development. It is an unity integrating supply of UESS and demand of urban development that link, influence, and restrict each other. The conflict between the infinite demand of urban socioeconomic development and finite supply of UESS determines the threshold value of UECC. Employing the theory of ecological carrying capacity (ECC) and considering its threshold, we analyzed the situations of imbalance between supply and demand of ECC, which results in an urban ecological crisis. The imbalance, i.e. the threshold of UECC, is usually caused by a few limiting factors. Therefore, corresponding urban ecological regulation (UER) should focus on the imbalance between supply and demand of these limiting factors. Having identified the limiting factors of UECC, we gave the regulative layers, concrete measure, and the blueprint of UER. In a word, the UER is actualized from three levels including natural, functional, and human levels, by the means of regulating supply or demand of limiting factors according to actual situations. By these efforts, the steady and sustainable urban development will be obtained finally.