In order to render large scale ocean waves in real-time, an effective method is presented. Firstly, a novel geometry model based on LOD (Level of Detail) is used as the ocean surface, and the Gerstner wave is applied on GPU to simulate dynamic ocean wave and choppy wave. A bump mapping texture is utilized on areas far from the eyes for improving rendering performance, and the animated bump mapping textures are used to enhance the rendering effect of ocean surface. Secondly, the sun and sky reflections are achieved via cube mapping texture. Phong light and Fresnel reflection are discussed and applied. Special effects such as cloud shadow and whitecaps based on texture animation are implemented. Experimental results show that the method can be used to render a 90 km ocean scene interactively in real-time and has been applied to a flight simulator successfully.