In view of China’s economy achieves rapid development, technology and science change with each passing day and gradually integrate into our life. Accustomed to the intelligent age, higher requirements caused by the design of public facilities is proposed. The public facilities of the historic block are not only the effective guarantee of people’s life, but also the embodiment of the urban culture. Therefore, it is necessary to take the initiative to respond to the rapid change of the demand brought by the urban change and create a pleasant cultural space. However, the historical block is large in scale and rich in details, and the design of its public facilities requires not only a broad range of material resources, but also a plethora of manpower. In order to further decrease the design cost and significantly improve the design level, the virtual system of 3D historical block based on VR is designed, and the public facilities are designed in the virtual system. Furthermore, the design and evaluation system of public facilities based on BP neural network is designed, which simplifies the process of design evaluation and program modification through real-time design evaluation and greatly improves the design efficiency of public facilities in historical blocks.