How to ensure services compatible at the behavioral level is an important issue for services integration and collaboration in a seamless way.Based on the proposed concept of service view,a formal definition of behavioral compatibility between services is proposed.Then,aπ-calculus-based method is proposed to qualitatively determine and quantitatively compute behavioral compatibility.First,it transforms service behaviors and interactions between services into n-calculus processes using an algorithm automatically.Second,it determines qualitatively whether two services are behavioral compatible with the help of operational and transitional semantics and a formal deduction.After that it proposes an algorithm based on the Expansion Law to compute the compatibility degree between services quantitatively.The application of the method in the scenarios of composing and replacing services dynamically shows that it is very useful for correctly building and reliably executing service compositions.