In order to meet with requires of high reality and verisimilitude of walkthrough system of 3D roadway, the paper proposed a common framework model of walkthrough system of 3D roadway based on engine-mode. It discussed functions and working flow of main control module, physical system module and rendering system module in the framework in details and gave solution scheme of the system under B/S mode. The simulation result showed that walkthrough system of 3D roadway based on engine-mode has higher degree of simulation and faster speed of walkthrough comparing with walkthrough system of 3D roadway based on basic API.