Abstract: Using the rooted theory to analyse the first-hand interview data of enterprises and users, seven patterns of knowledge co-creation behaviours and the influencing factors at the community and user levels are explored, and a theoretical model of the enterprise-user knowledge co-creation system in virtual brand communities is constructed. It is found that: enterprise-led and user-led knowledge co-creation behaviours jointly construct the product development knowledge base and the product promotion content base; the theoretical framework of enterprise-user knowledge co-creation in virtual brand communities is proposed, and the influencing paths of community factors and user factors on knowledge co-creation behaviours are systematically revealed, which finally lead to the response results of the product development knowledge base and the product promotion content base. Through theoretical analyses and empirical tests, it provides new theoretical perspectives and management suggestions for promoting enterprise-user knowledge co-creation, and fills the research gap in the existing literature.