Bending of flexible screens often leads to issues such as device damage and adhesive layer delamination. Therefore, it is essential to understand the strain distribution in the protective layer during the bending process. This study presents a method for measuring the strain in a flexible screen during bending, utilizing digital image correlation. The method enables synchronized full-field strain measurements in the protective layer while simultaneously capturing speckle pattern images applied to the screen surface. Subsequently, we calculate the bending plane equation based on matching point coordinates, revealing the relationship between bending angle and strain. Experimental results validate the effectiveness of this approach in providing comprehensive strain data for the protective layer at various bending angles. Consequently, this method quantifies the strain occurring on the screen and provides insights into stress distribution during the bending process.