Offshore platforms are immersed in seawater for a long period of time and need to withstand harsh environmental conditions such as wind and seawater impact. In this case, unfavorable factors such as environmental corrosion, adhesion of marine organisms, material aging, structural defects and mechanical damages will lead to the attenuation of platform structural components and overall resistance. It affects the safety and durability of the structure in use. In this paper, a water-air integrated offshore platform damage detector is designed. The head of the fuselage adopts the kingfisher bionic design, and the wings are folded. Compared with a conventional UAV, the water intake resistance is reduced by more than 50%. The wing vertical propellers and tail adjustable propellers can form three vertical propulsions to realize hovering detection. In addition, the aircraft utilizes a high-definition camera detection method with improved YOLO algorithms and a three-dimensional sonar detection system to design the integrated detection system. Compared with current detection methods, the confidence level is high, and the false alarm rate is significantly reduced.