The purpose of the study was to understand the educational role of an educational social network service (SNS) in eLearning environments. A quasi-experimental research was conducted with forty valid college-students who took an eLearning class using an educational SNS that developed by K University in Korea. To address research questions, numbers of postings and replies were compared according to the learning styles of the leaner (independent, avoidant, collaborative, dependant, and competitive) and the feedback types of the instructor (reinforcement and corrective). Also, learning contexts were analyzed by Content Analysis method. As a result, more effective strategies of reinforcement and corrective feedbacks were needed. Also, students used SNSs for studying learning contents, confirming classroom schedules, encouraging participation and learning, and showing intimate friendship. Based on the results, suggestions were made including the necessity of providing more systematic feedbacks, leading optimal learning activities based on analyzing learning styles, and synthetic development of instructional strategies for learning effectiveness.