To run a smart E-Business or provide efficient Web service, a web services composition model is needed. Web services composition refers to the process of collaborating the heterogeneous web services. This paper presents a model of web services composition by using Case-Based Reasoning (CBR) techniques. CBR is applied in the process of service discovery, which is the crucial composition process. Our service composition model integrates the two behaviours of proactive and reactive service compositions. We will address dynamic composition and collaboration among services. The similarity feature of CBR is used for efficient service discovery. .