Abstract: The concept of custom commands is proposed to classify modeling commands into “net commands ” and “local commands”，so that the quantities of data being transmitted among clients were reduced greatly．And in this paper，the corresponding data structures for net communications were organized to meet the requirements of collaborative design．Based on the above research and the technology of feature-based modeling，a3D part collaborative design tool with C/S architecture is developed，which implemented the collaborative parametric design of part level products in a network environment．