The wind power collection using DC grid technology has been considered as one of effective solutions for large offshore wind power collection. The paper analyses the technical requirements for collection of large offshore wind farm power using DC grid technology, and studies the typical DC collection grids for offshore wind power equipped with the wind turbine of DC power output type, then builds the equivalent model of DC wind turbine which is based on the electro-mechanical transient characteristics. On this basis, the coordinated control strategy of DC wind farm collection and sending system is designed in detail, the stable operation characteristics of DC wind farm are discussed in this paper. The simulation results validate the effectiveness of the presented typical topology and relative coordinated control strategies for stable operation of wind farms using DC grid technology.