Researchers believe that social network such as facebook is an innovative knowledge sharing technology. The increase use of social network each year has shown that these effective medium can be extended beyond simple communication within a community. A few studies were conducted to explore knowledge sharing behaviour among social network users. However, research study that focuses on online business network users still has not been explored yet. Communication among online business network users within the community is important in sharing and exchanging knowledge. This will lead to factors that motivate them to share knowledge through online communication. Identifying factors in online knowledge sharing behaviour is essential in order to improve their communication and business activities. Thus, this research is intended to identify the most important factors in knowledge sharing behaviour among online business network users by using Analytical Hierarchy Process (AHP). AHP technique is used to prioritize eleven factors which are reciprocal benefits, altruism, mutual trust, identification, reputation, social network ties, shared vision, shared interest, computer self-efficacy, technology innovation and controllability. This study will benefit virtual entrepreneurs as it provide ways to recognize the important factors in sharing knowledge and to improve their communication, business activities and contribution to the existence of long term sustainability of online business through social network.