Abstract: In networked software, the large numbers of domain asserts of multi-level and various granularity is obtained through domain modeling. It is necessary to organize them by use of division of problem domain in order to reuse them conveniently and then provide services on-demand. Therefore, cohesion and coupling is used to measure the rationality of the division, and to guide the merge and subdivision of problem domain. By this way, it can provide a strong guarantee to achieve the strong cohesion and weak coupling of problem domain and improve the domain model reuse convenience ultimately.