In recent years with the rise of HVDC transmission technology, wind power using MMC and network is widely studied and applied. However, the conventional HVDC integrating wind power methods have less control dimension, so that can not match the flexibility of the load. In this paper, a permanent magnet direct-drive wind farm is connected to the MMC with full-bridge sub-modules in the wind power integration system, which has the characteristics of AC and DC current independent control. The system can be stably operated at low DC voltage to avoid the accident of the turbine cut off the net caused by load reduction. When the DC voltage drops, the system constantly maintains the AC voltage, so that the wind farm can run normally. Finally, the simulation is carried out in PSCAD / EMTDC. The results show the correctness of the proposed system and its control strategy.