The invention discloses a sealing gasket strip for preparing large and ultrathick organic glass and a surface protection method. The section of the sealing gasket strip takes the shape as shown in figure 1, and d, h, r1 and r2 thereof can be adjusted according to a thickness of the prepared organic glass. A material for preparing the sealing gasket strip is rubber. The sealing gasket strip has a certain hardness and elasticity, so that the sealing gasket strip can be correspondingly compressed along with shrinkage of a polymerization system to prevent influence on polymerization process from permeation-out of methyl methyl acrylate (MMA) and permeation-in of water caused by system shrinkage in the polymerization process. Polyvinyl alcohol is used as protection fluid; the protection fluid is brushed on the surface of the sealing gasket strip; a dried polyvinyl alcohol film can effectively prevent the sealing gasket strip from being swelled and dissolved by MMA in the polymerization process; the polymerization inhibition effect of components, migrated by the MMA solvent, of an adhesive tape on MMA free radical polymerization is prevented; and the requirements of preparing a large and ultrathick organic glass plate are satisfied. After the technology is adopted, the MMA polymerization process is stable, and the polymerization success rate of the large and ultrathick organic glass is greatly increased.