To explore architectural design methods for the renovation of old buildings within the context of existing stock, this study uses the renovation project of the old buildings in the Wutongshan Community of Luohu District, Shenzhen, as a case study. By integrating psychophysical theory with virtual reality(VR) technology, the research investigates the potential of VR as a design medium. A VR perception experiment was designed using digital models and a head-mounted VR interaction system. Subjective preference evaluations were collected for 16 renovation schemes of individual buildings within the site. Additionally, 10 design influencing factors were extracted across three dimensions: form composition, interface composition, and landscape composition. Using SPSS for correlation analysis, the study examines the relationship between design elements and public preferences to understand the factors that attract public attention in the renovation of old buildings. Results indicate that morphology elements such as landscape configuration, courtyard configuration, interface brightness, block richness, D/H value, and roof visual width in the scheme are significantly correlated with human spatial cognitive preferences. Based on the experimental results, the optimization strategy of the design scheme is proposed. Using VR technology in optimizing the external form design of buildings helps designers understand the spatial cognitive mechanisms of users. This paper proposes an interactive design optimization process through multi-party collaboration, which can be used as a reference for related design practices.