In the third issue of sociological research in 2021, Li Jun proposed that the study of class identity has attracted academic attention in recent years, but it has been lack of long-term change analysis. Based on the data of five social surveys in Shanghai in 1991, 1996, 2005, 2008 and 2013, this paper empirically analyzes the changes of Chinese urban residents' class identity and its decision model throughout the eras. It is found that from the 1990s to the beginning of the 21st century, people's subjective social status has experienced a benign transformation from "everything depends on money" to "multiple decisions" of education, occupation and income; However, the last decade has entered a new era mainly determined by assets (income and housing). At the same time, the subjective social status of social average has gradually declined over the years. The phased characteristics of urban social change determine the above changes of class identity. The macro-economic and social change characteristics of increasingly strong asset inequality have deeply affected people's subjective consciousness.