Abstract: Social interaction connects people in distance education. It affects and determines the quality and effect of online learning. The study based on Biggs 3P teaching model and uses the method of structural model equation to explore the role and influence of social interaction level on online deep learning. The results show that deep social interaction has a positive impact on learning motivation, learning strategies, learning engagement and learning outcomes, while shallow social interaction is weak. At the same time, learning strategies play an important role in deep learning and its outcomes.