Online learning ability has an important influence on the effect of online learning. This article uses research methods such as in-depth interviews and social network analysis to identify the relevant factors and specific relationships that affect medical students' online learning ability. The research results show that the main factors affecting medical students' online learning ability are the learner's ontological characteristics, course platform environment, teachers' individual characteristics and performance of classroom teaching. The learner's ontological characteristics are the most important factor. While the course platform environment and classroom teaching are affected by the learner's ontological characteristics, there is also a close correlation between the two; the influence of teachers' individual characteristics on the online learning is not so significant as compared to the other 3 aspects. It is recommended to pay attention to the characteristics of learners, enhance the direct influence of classroom teaching factors, optimize course platform environment, and strengthen teachers' capacity building, so as to improve the online learning ability of medical students.