Based on a laser emission system of aperture 600 mm, a rolling blinds sealing method was presented. For the rolling blinds, a curly replay structure was applied to drive the synchronous belt through the motor drive roll. At the same time, the rolling blinds was tightened by the elastic tightening mechanism to keep the blinds close to the seal plane to achieve the sealing effect. By theoretical analysis and numerical simulation of Finite Element Analysis, the sealing characteristics were studied. It can be concluded that the structure of the seal plane are the main factors affecting the sealing performance. By analysis and comparison, PVC is selected to be the material for rolling blinds. The designed structure is a sealed protuberance with a chamfering of 30° and thickness of rolling blinds is 0.5 mm. The Finite Element Analysis of the sealing characteristics shows that the center deflection of the rolling blinds is 6.269 mm. Under the limit load allowed by the design requirements, the stress of the rolling blinds is far less than the tensile strength of the material and will not be destroyed. The designed window satisfies the sealing requirements.