With the shortage of energy, solar power has become the most appreciative choice in the world. The performance of the solar modules has great relevant with the degree of crosslinking for EVA sheet. Motivated the three lamination tests on solar modules, the study proposed a simple regression model to describe the relationship between the degree of crosslinking and laminated time. Then, given the specification limits of the degree of crosslinking, the optimal laminated time can be derived. Next, by estimating the optimal lamination time accurately, the optimal laminated design can be obtained. Finally, a simulation study was conducted, and the results showed that the simulated values are quite close to the asymptotic values.