The digital protection and inheritance of cultural heritage is an important path for sustainable cultural development. This paper takes Fuzhou's "Shangxiahang" historical and cultural block as the research object and explores methods for digital protection and inheritance based on VR intelligent interaction technology. By constructing a 3D virtual scene of the "Shangxiahang" cultural block and combining the Unity engine with AI technology, an immersive experience system with virtual roaming, intelligent dialogue, and cultural dissemination functions is designed and implemented. The system not only enhances the immersion and interactivity of user experience but also improves the effectiveness of cultural knowledge transmission through intelligent NPC interaction and knowledge acquisition mechanisms. This study provides a technical implementation path and theoretical reference for the digital protection and innovative inheritance of cultural heritage, with certain practical and promotional value.