The structural vibration detection for large bridges is critical. A wireless measurement system based on Wireless Sensor Networks (WSNs) for large bridges was developed in this paper. The overall architecture of the wireless system is introduced; the design of wireless nodes and the principle of the central station are given in detail. Experiments are conducted in the laboratory and the Nanjing IV Yangtze River Bridge to verify the performance of the designed system. Experimental results show that the performances of the designed system are improved in the transmission distance. The system anti-jamming ability and data transmission packet loss rate are also improved compared to traditional wireless sensor systems. Meanwhile, with the external sensing interfaces, the system has a superior performance in characteristics of high sensitivity and ultra low frequency. It can easily and quickly carry out structural vibration detection for a large bridge in its construction, future operation, and maintenance periods with strong practicality and high application value.