Ocean Data Buoy with fixed-point, real-time, long-term, continuous and accurate data collection capabilities is a modern ocean observing tools and instruments. Therefore, the reliability of information is essential, which depends on the stability of the working buoy. While the waves are acting, the buoys are difficult to maintain their stability. Based on Computational Fluid Dynamics, the force situations of buoy at wave conditions are simulated by using Variable Operating Frequency method and Fluent software. The variation of lift and drag forces and the changing trend of movement of buoy are obtained. And then the numerical value of force is adjusted by changing the height of waterline. At last, the digital design of shell structure is carried out with SolidWorks to improve the stability of buoys in surface wave.