Based on self-determination theory, this paper aims to construct an index system of motivations of the participants of network micro-class community. Network questionnaire survey, exploratory factor analysis and confirmatory factor analysis were used to cluster seven participation motivations. The result showed that for users of network micro-class community, conformity motivation and emotional motivation are not main motivations; social motivation and information motivation are relatively important motivations. Interest, learning and sharing motivations are most important participation motivations of network micro-class community. Therefore, it is concluded that the elements of the network micro-class community are the subject, output and interaction.