Motivated by sustainable development requirements of global environment and modern cities, the concept of the Smart City has been introduced as a strategic device of future urbanization on a global scale. On the other hand, modern cities have built up developed information infrastructure and gathered massive city running data, and therefore are ready to face the coming of the Smart City concept, technologies and applications. An important peculiarity of Smart City is that the technology system is data-centric. The data science and technologies, such as big data, data vitalization, and data mining, play pivotal roles in Smart City related technologies. In this paper, we provide a comprehensive survey of the most recent research activities in data-centric Smart City. The survey is from an informatics perspective and all summarized Smart City works are based on data science and technologies. This paper first summarizes the variety and analyze the feature of urban data that are used in existing Smart City researches and applications. Then, the state-of-the-art progresses in the research of data-centric Smart City are surveyed from two aspects: research activities and research specialties. The research activities are introduced from system architectures, smart transportation, urban computing, and human mobility. The research specialties are introduced from core technologies and theory, interdisciplinary, the data-centric, and the regional feature. Finally, the paper raises some directions for future works.