Ensuring the correctness and reliability of large-scale resource sharing and complex job processing is an important task for grid applications. From a formal method perspective, a grid service chain model based on state Pi calculus is proposed in this work as the theoretical foundation for the service composition and collaboration in grid. Following the idea of the Web Service Resource Framework (WSRF), state Pi calculus enables the life-cycle management of system states by associating the actions in the original Pi calculus with system states. Moreover, model checking technique is exploited for the design-time and run-time logical verification of grid service chain models. A grid application scenario of the dynamic analysis of material deformation structure is also provided to show the effectiveness of the proposed work.