Objective To explore the learning behavior characteristics of social learners in MOOC. Methods The data were retrieved from the MOOC data of two sessions of Health Assessment at Sun Yat-sen University. We analyzed the study behaviors of the whole learners and different types of learners. Results A total of 8 173 registered social learners were enrolled in the two sessions,of which 550（6.7%） achieved the final score,and the participation rate of them showed a decreasing trend in all tests（R ²=0.513,β=-0.161,F=9.479,P=0.013）. There were 34 committed learners（6.2%）,233 early dropout learners（42.4%） and 283 irregular learners（51.5%） among learners who achieved final results . Except for the first test,the final test and the two tests（laboratory examination and imaging examination）with relatively higher professional requirements,there was no significant difference between the three groups in most tests. In terms of discussion,the proportion of committed learners participating in discussion was the highest（76.5%）,and non-committed learners were more willing to participate in teacher-guided and purposefully case discussions（P<0.05）. Conclusion The majority of social learners participating in MOOC were non-committed learners（early dropout and irregular learners）.There was no significant difference in the learning effects of different types of learners in most projects（except those with high professional difficulty）.In terms of online interaction,most committed learners actively participated in case discussion and free discussion,while non-committed learners preferred to participate in case discussion rather than free discussion.