The invention provides a method and device for determining impedance of a direct-driven wind turbine generator set based on control hardware-in-the-loop. The method includes the following steps: firstly, calculating the total delay of a simulation interface, and then determining the positive-sequence impedance and the negative-sequence impedance of the direct-driven wind turbine generator set according to a current signal delay transfer function and a voltage signal delay transfer function of a grid-side converter of the direct-driven wind turbine generator set that are pre-constructed. The obtained positive-sequence impedance and negative-sequence impedance of the direct-driven wind turbine generator set have high accuracy, and a simple implementation process is realized. The method for determining the impedance of the direct-driven wind turbine generator set can provide a theoretical basis for the correction of subsequent impedance scanning results; compared with an off-line simulation mode, the characteristics of flexibility and convenience of simulation model scanning can be inherited, and the error that an off-line model ignores the equivalent of a real controller can also beovercome; and compared with an impedance actual measurement mode, the control characteristics of real devices can be inherited, the technical implementation difficulty of high-power linear amplifierscan also be reduced, and meanwhile, the construction cost can be greatly reduced.