According to need hierarchy theory，this study put forward that we could regard sense of social security，sense of social trust，sense of social fairness and sense of social support as people’s evaluation on needs satisfaction；therefore these four needs constitute the motivational components in behavior of social mentality. Based on online survey towards 570 netizens，this study analyzes the status of needs satisfaction among the public，and the corresponding differences in social class. The results show that participants are most satisfied with their social support，followed by social fairness and social trust，they are most unsatisfied with social security. For netizens with lower income and social class，they have lower sense of social security，worse sense of social trust，weaker sense of social fairness，and also less perceived social support.