Abstract: Compared to existing AC-pooled wind power systems, the DC pooling method uses a high-variable-ratio and large-capacity DC converter to boost and aggregate DC-output wind turbine generators, which reduces system losses and facilitates long-distance DC transmission. The high number of power electronic equipment in the system requires impedance modeling and oscillation characterization urgently. To this end, a two-port impedance model of the input-parallel output-series Boost full-bridge isolation converter is first proposed. Based on this, an impedance model of the send-out port for the series-parallel pooling topology wind farm is established, and a multi-harmonic linearization method is used to establish the DC-side input impedance model of the modular multilevel converter (MMC). The stability analysis of the DC pooled wind power system is carried out according to the frequency characteristics of the small-signal model. Finally, the time-domain simulation model of the system is built in MATLAB/Simulink to verify the correctness of the established impedance model and the conclusions of the system stability analysis.