As the knowledge economy age comes, knowledge management (KM) is a crucial factor for retaining competitive advantage for many companies. Besides applying an appropriate knowledge management schema for organization, information technologies will be the key factor to enhance the ability of KM system for knowledge collection, aggregation, storage, diffusion and sharing. In this study, a prediction model of user information preference for knowledge sharing system is proposed by combining fuzzy set theory with grey prediction to provide appropriate information which meet user's requirements. According to preference degree of each user in a period, the proposed model will predict the tendency of user's preference and provide suitable information to meet the requirement of each user in accordance with his/her preference trend in a knowledge sharing system immediately.