The small and medium-sized enterprises have been the most active and potential new sources of economic growth in our country. Based on the concepts of network organization and enterprise competitiveness,this paper expounds a enterprise ' resources allocation system,and constructs its structural model. At the same time,by the method of analyzing the reliability of a system,this paper studies the effects of a cross-boundary network organization,which relate to the information efficiency of a resource selection sub-system for a small and medium-sized enterprise,and draws a conclusion that taking part in a network organization can enhance the enterprise competitiveness .This viewpoints and the way of thinking would provide some suggestions for a small and medium-sized enterprise to focus its limited resources on core competence best.