The ocean thermal energy is abundant and is ready for clean energy output. Firstly, the global total is about 40 billion kW. The ocean thermal energy conversion (OTEC) is clean and renewable, the power generation is stable, and the energy stored capacity is high. Active exploitation of ocean thermal energy resources is of great significance to realize the strategy of maritime power. Next, in view of the efficiency limit of a traditional OTEC, authors propose an approach of multi-energy complementary system to improve the system efficiency based on OTEC. This approach integrates solar energy, wind energy and energy storage into a complementary OTEC system; this complementary system sets parameters at the system level. For example, a 1 MW integrated power generation system is designed. Moreover, by calculating a theoretical model, researchers investigate the system with computer aided design and simulation. The efficiency of the complementary OTEC system with solar heating can reach 12.8% and the comprehensive efficiency can reach 18.6%. Furthermore, there are many favorable by-products of OTEC that are considered beneficial for the eco-system. Finally, in this paper, the basic principle and working process of the approach are analyzed, and the system efficiency is calculated. The results show that in comparison to the traditional OTEC, the complementary system can improve the ratio of power generation output efficiency, stability and ocean energy utilization.