In this study，we collected a total of 15870 questionnaires through online questionnaire survey using mobile phone APP，which has about 1.1 million online samples in China. We anticipate to present the basic situation of urban residents’ sense of social fairness，and find out the features of social comparison in the formation of a sense of fairness. The results show that respondents’ sense of fairness are at a moderate level；the higher the respondents’ education level，the lower their sense of fairness will be. The respondents are especially satisfied with the fairness situations in compulsory education，political rights，and public health. People generally choose friends，colleagues as their reference group，to reach a judgment of their status of income，health，family harmony，and job prospects. But the concerns during this social comparison process also differ among age groups. Most people believe that their income levels，living conditions，and social status et al. are in a moderate level，and the gap between themselves and others in these respects are acceptable.