Based on the mobile phone traffic big data, this paper measured the activities of residents in the “Micro City” of Yancheng, China. Then we built the relationship between the residents’ activities and the land utilization intensity considering the layout density and coverage area of the base stations to analyze the characters of spatial and temporal change of activities. This paper further analyzes the main influencing factors of activities by questionnaire survey. The result shows that the activities intensity is significantly correlated to the residential area volume rate, environmental suitability, living convenience, and transportation convenience. Among them, transportation convenience is the most significant factor in working days, while on weekends and holidays is daily living convenience. Finally, we put forward the suggestions on residential structural optimization.