In order to reduce the energy consumption of kelp drying, improve the drying quality and the efficiency of the drying system, modeling and research were carried out based on thermodynamics and heat transfer theory, and solar-thermal coupled drying system for kelp with sunlight greenhouse as the main body, air heat pump and heat collecting plate as heat source was designed. Drying temperature and time were set through the touch screen for kelp drying,  temperature sensor, humidity sensor and light sensor were used for measurement, and data was recorded for analysis. The drying system could recover the residual heat discharged during the drying process, dehumidify the residual heat, and then repeatedly use the heat; the solar thermal collector stored the heat energy in the water tank for secondary drying to save energy. The results showed that when the maximum air temperature was 27.5 ℃, the moisture content was about 90%, the weight of fresh kelp was 60.32 kg and the drying time was 10 h, the new kelp drying system had a good effect if the moisture content of dry kelp was 14.5 %, the weight of dry kelp was 6.9 kg and the lowest quantity of electricity was 3.91 (kW·h) / kg. The research has provided a new technical method for the large algae drying, and the technology is suitable for promotion in large algae drying of medium and large enterprises.