Abstract: To address the coupling of dynamic characteristics at different scales during wind turbine generator system modeling, a multiscale dynamic cascaded extended modeling scheme was proposed for wind turbine generator system. Based on this scheme, a 10 MW wind turbine generator system simulation model and a multi-scenario virtual testing method for the complete machine were designed. This method enabled decoupling of the operational characteristics of the wind turbine generator system from the vibration and load characteristics of each component in the gearbox. It allowed efficient simulation of the flexible multibody dynamic characteristics of wind turbine generator system and flexible multi-scenario application analysis. The constructed 10 MW wind turbine generator system model was subjected to operational simulation and multi-scenario testing using various simulation software. The operational characteristics of the complete machine and the vibration and load characteristics of the gearbox model under different operating conditions were analyzed. Results show that the designed 10 MW wind turbine generator system multiscale dynamic cascaded extended simulation model achieves the expected control targets for the operational characteristics of the complete machine, and the vibration and load characteristics of the gearbox model under different operating conditions all satisfies the design requirements.