Abstract: Wireless sensor networks(WSN) is one of enable technologies in the structural health monitoring (SHM). Through intelligent, self-organizing means, it will test a variety of different objects and different working principle of the sensor nodes connected into a network and integration with data processing functions. In this paper the key issues of WSN applied in SHM were discussed, including integration of different types of sensors with different operational modalities and sampling frequencies, issues of transmission bandwidth and real-time ability, the wireless transmitter frequency, topology, and data fusion and integration, energy saving and self-powering. In FP7 project ‘Health Monitoring of Offshore Wind Farms’ project, the above issues were explored.