The concept of modularity works not only with physical product but also be used to create flexible service. Modular service architecture reduces the complexities of operation while at the same time speeding in bringing new products to market. In this paper, we create a novel methodology for identifying modules in service. Through service process analysis, a function relation matrix is examined to define the relationships between the service elements. The reintegration process by using ward's method and K-means clustering is also analyzed. Finally we test such approach on the specific case of an express mail delivery service.