Nowadays, knowledge-intensive enterprises, which offer knowledge-based products and services to the market, play a vital role in the knowledge-based economy. In the global networked age, collaborative business services have raised as one of the most important knowledge-intensive services that help enterprises to gain the competitive advantage. These services greatly depend on the ability to use network architectures to collaborate efficiently with business partners. This paper introduces the KB-CBSM (Knowledge-Based Collaborative Business Service Modelling) approach, which aims at providing a conceptual foundation for modelling effectively and improving incrementally collaborative business services in knowledge-intensives enterprises. The paper begins by presenting the necessity and principles of the KB-CBSM approach. Next, it presents the conceptual foundation that consists of three levels: Service value creation network, Service system and Service levels. The paper continues with a discussion and review of the relevant literature and ends with the conclusion and suggestions for further research.