Abstract: Urban public space is an open place for people to engage in social activities. It is of great significance to study the measurement of its vitality. People and their activities are the main body and external manifestation of the vitality of public space. Traditional measurement methods are often indirect reflection of the space vitality. Big data can fully reflect the behavior characteristics and spatio-temporal laws of crowd activities. Thus, it is possible to truly describe the essence of public space vitality. From the perspective of reflecting the stability, aggregation and diversity of human activities, this paper puts forward the evaluation system and quantitative calculation method of public space vitality based on big data. It points out that the study of big data quality and applicability, public space vitality evaluation and coupling mechanism of public space vitality with the physical space should be the future research directions.