With the constant development of economy and society，the scale of middle-income group in China has expanded a lot. The proportion of middle-income groups is comparatively higher in the developed area especially as Beijing，Shanghai and Guangzhou. The survey report summarizes the current status of the middle-income group，which is based on the random sampling survey in the three metropolises mentioned above. The report focuses on the characteristics of economic status，working conditions，lifestyle，class identity and social life of the middle-income group on the basis of the presumption which is about the scale of the middle-income group in these cities. Through the empirical research，we conclude that：1）First of all，the middle-income group has strong economic capabilities. The consumption and economic development will be highly motivated and promoted by the continuously expanding scale of the middle-income group；2）Secondly，the social attitudes and values of the middle-income group contain abundant positive energy，which will plays a significant role in the guidance of values to the other social groups；3）Moreover，the middle-class is the main force of the market economy as the group is shaped by the market mostly；4）Last but not least，the expansion of the scale of the middle-income group in Chinese society will be of essential importance to avoid the polarization and shake off the middle-income trap，which means the Chinese social structure will be more reasonable and head for the Olive-shaped society.