In order to explore the application value of virtual reality technology in urban micro-renewal, the immersive experience design of pocket parks is taken as an example to study the impact of multimodal interactive environment on spatial perception and public participation. An immersive design system based on high-precision 3D modeling, physical engine simulation and biological data feedback is constructed to optimize the landscape layout, walking flow and environmental parameters, and to enhance the accuracy and scientificity of spatial experience. We analyze the role of multimodal data fusion in user behavior perception, scene adaptability assessment and decision optimization. The results show that virtual reality technology can effectively improve the accuracy of spatial cognition, the fluency of interactive experience and scenario understanding, and shorten the design iteration cycle. The scenario optimization mechanism based on physiological signal feedback enhances the applicability of the scenario, and provides a quantifiable assessment system and technical path for the renewal of small-scale spaces in high-density urban environments.