VTD (VirtualTest Drive) is a complete modular simulation tool chain developed by German VIRES company for ADAS, active safety and autonomous driving. VTD currently runs on the Linux platform, and its functions cover road environment modeling, traffic scene modeling, weather and environment simulation, simple and physically realistic sensor simulation, scene simulation management, and high-precision real-time image rendering. It can support the full-cycle development process from SIL to HIL and VIL, and the open modular framework can easily co-simulate with third-party tools and plug-ins. VIRES is also a major contributor to the widely used open formats for autonomous driving simulation OpenDrive, OpenCRG and OpenScenario, on which VTD functions and storage are also based. The simulation process of VTD is mainly composed of three steps: road network construction, dynamic scene configuration, and simulation operation.