Knowledge plays an increasingly important role in business, company, and organization,it is the ability for organization to learn and assimilate new knowledge in orderto make plans or business progresses. However, when comes to the tacit knowledge,in most cases, as Polanyi (1969) said ”we can know more than we can tell”, whichmeans in our daily lives, most of the knowledge stored in our brain can not be expressedout to others easily, we call this kind of knowledge ”tacit”. Therefore, tacitknowledge holds most part of our knowledge - and at the same time - harder to identifyand share.There is an popular approach called ’Community of Practice (CoP)’ which aimsat creating and sharing knowledge through informal practicing and learning. Thus,in this study, a qualitative research is desired to be made on the approach of communityof practice as well as its effects on tacit knowledge sharing. The purpose of thisstudy is to understand the pattern of sharing tacit knowledge among communitieswith social communication technologies (Tencent QQ) embedded, and to explorethe mechanisms of generating and transferring tacit knowledge with ”community ofpractice”.