Due to the concealment of underwater engineering, the detection and monitoring of hydraulic structure construction is often more complicated and difficult than surface engineering. Cofferdam construction inspection and settlement construction quality inspection, especially to ensure the accuracy and efficiency of inspection in complex environments, have become an urgent problem to be solved in underwater engineering quality inspection and monitoring. This project designs an offshore fixed-point monitoring device based on wave energy and piezoelectric effect energy. The invention provides a wave power generation system. The system include simple structure, reliability and stability The fixed-point monitoring device combines the cantilever float device, the gas storage tank device and the piezoelectric ceramic energy supply device to provide the marine monitoring device with energy for automatic water surface monitoring, fixed-point and data collection. Finally, the comprehensive utilization of sea surface wave, compressed gas energy storage and piezoelectric effect energy is realized.