In order to investigate the effect of different barrier packaging materials on the preservation of harvested lettuce. Lettuces were encased in modified atmosphere packaging (MAP) with LDPE, PE, HDPE and EVOH/PE films and stored at 4℃, while the ones without packaging were used for comparison under the same conditions. During storage, the gas composition in packaging, sensory quality, weight loss, chlorophyll content and relative conductivity of lettuces were measured regularly. On the sixth day, lettuces in the control group lost the commodity value due to serious water loss. In the EVOH/PE group, O₂ was running out and the CO₂ ratio reached 203%. It also produced an alcohol smell in the bag. The O₂ ratio in the other three groups decreased first, then fluctuated within a small range, and the proportion of CO₂ increased first and then relatively stable. The preservation effect of HDPE group was the best, and the storage time could reach 18 days. Barrier suitable packaging materials could effectively improve the preservation effect of lettuce, therefore their shelf life was extended.