The control methods for greenhouse external shading are divided into manual control and automatic control. Manual control is suitable for small greenhouses, while automatic control, also known as electric control, is suitable for large greenhouses, offering simplicity and high efficiency.The electric part uses variable-speed motors as the power source to extend and retract the shading curtain synchronously through the rotation of mechanical linkages, reliably achieving the deployment and retraction of the entire shading system. This effectively controls the temperature inside the greenhouse. If the temperature still remains at the upper limit, it can be appropriately combined with opening skylights, side windows, and the wet curtain fan water circulation system for forced cooling.