Process level is one of the important characteristics of smart substation, which is different from conventional substation. Its networking scheme directly affects the realization of protection and control function and the investment of network equipments. Based on the analysis and comparison of several kinds of typical process-level network topological structures and sampling value transmission protocols, a suitable process-level network scheme for smart substation is suggested in this paper. Combined with the current situation of substations, the design examples are also presented in aspects of equipment selection and functional requirements.