The system complexity is one of the factors that plagued urban ecosystem (UE) research and management. According to the general system theory, the complexity of UE can be divided into structural complexity, the complexity of the process, the complexity of system behavior, the functional complexity and emergence to the overall complexity. The reliable systematic analysis models and tools can help researchers and managers to deal with this challenge. Sensitivity model developed by Professor Vester, who was known as the great master of system thinking in Germany, was committed to addressing the complex issues in daily urban management practices. Of course, the model had taken remarkable achievements in the range of practical applications. The networked thinking and biological cybernetic (or bio-cybernetic) perspective are Vester's core ideas and the philosophy basis of the sensitivity model. The model framework was divided into three hierarchical levels: the bottom was the level of information organization mainly including data collection and screening process; following was the level of systematic cybernetic interpretation, emphatically mining the knowledge about system structure, interaction between parts, and so on with the aid of the cybernetic criterions; finally, the highest level, system comprehensive evaluation, gave an overall and integrated assessment of the system structure and behaviors via the eight bio-cybernetics principles. For the convenience of model users, the model was broken down into nine standard steps, each of which contained a number of useful mathematical analysis tools. In the model, Professor Vester also explicitly put forward a four-level systematic cybernetic indicators (or characteristics) to help advanced users easily form their system thinking. Sensitivity model itself had made many outstanding contributions. In detail, the model provided an integrated methodological framework for dealing with complex issues for the urban ecosystem research; it, most importantly, also provided a novel system regulation theory with his bio-cybernetic approach; in addition, it also provided a series of easy-to-use systematic analysis tools, which enriched the existing analysis methods. However, it also had some limitations. Specifically, the model itself wasn't perfect and just stated the concepts and framework, still stuck in the stage of paradigm description; the bio-cybernetics view was with a certain degree of naturalistic bias, and may not be entirely suitable for the urban ecosystem; it should be noted that the model have not been widely used in the world in the three decades of the model developed, in despite of its strong academic value and the potential for practical application, because of Professor Vester rarely writing in English and communicating with other scholars in other languages. These experiences and lessons learned provide valuable inspiration for the future modeling work of urban ecosystems. The sensitivity model is equivalent to providing a blueprint to create new models. According to specific targets, researchers can develop many more specific models on the basis of the sensitivity model. It must be point out that the sensitivity model needs to cooperate with other quantitative simulation model to address successfully real-world problems. Ideally, the modelers can start using the sensitivity model for better understanding of the system, and then establish a more accurate simulation model to improve the quality of the modeling work. In any case, the ultimate purpose of modeling work should be to improve people's understanding of urban ecosystems, and ultimately to support the urban management practices.