With the rapid development of virtual reality technology, the way we use the computer to display 3D models of realistic scene has become a research hotspot. The system based on Unity3D platform is constructed by using 3DMax to build the scene, combining Unity3D's prominent interface interaction technology to form Virtual Roaming System of Nanchang No.1 Metro Line. Finally, through the external link about ground station panorama, the system has integrated function of roaming subway station both inside and outside. The result shows that virtual roaming system can bring users intuitive roaming experience.