The research designed a new method to evaluate thermal damaged cells. Polarization microscopic imaging was performed on onion cells and epipremnum aureum cells. By comparing and analyzing the changes in polarization characteristics of cells before and after thermal damage, relevant information is obtained. The experimental results indicate that the polarization microscopic imaging technique is effective in identifying normal cells and heatdamaged cells and evaluating the degree of thermal damage. Polarized microscopic imaging reflects changes in cell morphological structure more clearly than microscopic intensity imaging, it shows good development prospect in the study of biological samples and disease diagnosis. Polarization microscopic imaging technique is rapid, nondestructive, effective, and it is a new method for identifying and evaluating the degree of cell damage.