As an essential part of the urban ecosystem, socioeconomic factors can reflect the characteristics of residents and measure their well-being, which has developed into an indispensable content of urban ecological research. However, the standards and frameworks for the rational and effective use of socioeconomic factors in urban ecological research have not been adequately studied. What socioeconomic indicators are commonly used in urban ecological research? What are the major data sources for these indicators? What research questions can be explored with socioeconomic factors? This study reviewed scientific outputs from the 11 urban long-term ecological research sites around the world to answer the above questions. The results indicate that the most commonly used socioeconomic indicators include general information of population, perception and willingness, and behavior. Urban ecological studies have widely used the former two categories. The principal data sources of indicators include statistical data or census data collected by government agencies, commercial data, and independent surveys conducted by researchers. Integrating socioeconomic factors into urban ecological research would facilitate studies investigating the coupling effect of humans and nature in the urban system. In recent years, despite of the rapid development and the rising status of urban ecological studies in China, the consideration and utilization of socioeconomic factors are still lacked, which may deviate Chinese urban studies from the international mainstream research direction of global urban studies. Data accessibility poses great challenges to urban researchers in China. We argue that opportunities lie in the widespread application of big data, establishing a data-sharing mechanism, and better use of existing public data.