As an important component of urban green space, city park plays a irreplaceable role in improving residents’ quality of life and promoting social integration, etc. and it vividly practices the concept of “people-centered urban development”. Aimed at the shortcoming of traditional appraisal method for cultural service in the ecological system in identifying service type and capturing emotional dynamic, on the basis of social media user comment data, this paper constructs the evaluation framework for cultural service of the ecological system that merges probability theme model and sentiment analysis, and taking four typical city parks in Shanghai as the empirical object, it systematically identifies and quantifies the type of cultural service in the ecological system of park and its public perception characteristics; it analyzes the emotional distribution characteristics of users of city park and multidimensional influence mechanism on that basis, and further puts forward the strategy for improving cultural service in the ecological system of park, so as to provide theoretical basis and practice reference for the dynamic evaluation and service optimization of cultural service in the ecological system of city park, and boost high quality development of urban green space and improvement of public well-being.