A more challenging problem for Web Service reconfiguration is to reconfigure services dynamically on demand. This paper proposes the dynamic reconfiguration method for Web Service. A policy based framework supports three levels reconfiguration strategies that separate reconfiguration from application. This framework includes three conceptual layers: change instruction, reconfiguration management, and application management. The reconfiguration is implemented in two phases by two layers: semantic analysis phase, and reconfiguration policy specification phase. The semantic analysis base on OWL-S is provided. A policy based on reasoning model addresses the dynamical reconfiguration in which systems can be controlled at a meta-level without changing their underlying implementation. Five issues concerned with consistency, policy conflict, security, fault tolerance, and configure schedule during period of dynamic reconfiguration are applied in our dynamical reconfiguration to guarantee the consistency, policy application, security, fault tolerance and time consume.