In the current Internet era, the available resources of small and mediumsized enterprises (SMEs) have gone beyond the extremely limited scope of their own resources to the external environment, forming a resource space jointly defined by identity boundary, competence boundary and efficiency boundary, which affects the realization of opportunities. For the reasons of weak hard power and highly flexible action, SMEs rely on and are good at cooperation based on soft power, using resources and identifying and developing opportunities. This paper analyzes by dimension and classification, and takes science and technology-based SMEs as a sample to confirm that the expansion of resource competence and identity boundary are helpful for SMEs to successfully identify opportunities, and resource efficiency boundary is helpful for opportunity development. Soft power at the social level enhances the role of resource identity and competence boundary on opportunity identification; and soft power at the organizational level positively regulates the impact of resource competence boundary on opportunity development. These two categories of soft power will weaken the function of the other sides. From the perspective of opportunity identification and development, the research results provide detailed action reference for targeted expansion of multi-dimensional resource boundaries, rational acquisition and application of different types of soft power.