The invention discloses an insulation device special for greenhouse overcoming the tedious operation of the existing greenhouse insulation technology. The device is characterized by comprising a drivemotor, a bearing wall, a roller shutter device, cotton wool, a cover net and a slideway; the bearing wall has a rectangular solid structure; the roller shutter device is a circular column; the covernet has a net structure; the area of the cover net is identical to that of the cotton wool; the cotton wool is fixed on the cover net; the roller shutter device is connected with one side of the covernet; the drive motor and the roller shutter device are connected to form an electric loop; two parallel sides of the cover net slide in the slideway. This design is simple, convenient, low in cost and easy to promote.