In this paper, a complete sequence impedance model of PLL-based grid following direct driven wind turbine is established in a modular way. First, establish the harmonic relationship of the generator side model, then establish the harmonic relationship of the grid side converter, and finally, associate the two harmonic relationships through the transitive relation of the DC bus, and solve them together to obtain the complete sequence impedance model of PLL-based grid following direct driven wind turbine.