The work aims to explore the packaging materials suitable for storage and preservation of postharvest brassica pekinensis. The brassica pekinensis was packaged with four polyethylene films of different thickness (10, 20, 30, 40 μm). With the original packaging film sold in the market as the control, the quality changes after storage at (23±2)℃ for 28 days were measured. Then, the selected films were used as research objects to further analyze their effects on the quality of postharvest storage of brassica pekinensis. Compared with other film packaging, the 30 μm thick polyethylene film packaging material had the best preservation effect on the brassica pekinensis, and the soluble sugar, protein and MDA content were respectively 13.49 mg/g, 3.79 mg/g and 1.51 μmol/g. Compared with the control group, the 30 μm thick film packaging could effectively inhibit the growth of the total number of bacterial colonies on the surface of the brassica pekinensis, delay the occurrence of decay, and maintain high content of ascorbic acid, total phenols, soluble sugars, total glucosinolates and sulforaphane. The results of comprehensive evaluation by principal component method also exhibited that the 30 μm thick film packaging had a better effect in slowing down the deterioration of brassica pekinensis. The 30 μm thick polyethylene film package can maintain the storage quality of postharvest brassica pekinensis in a better way and it is the suitable material for packaging, storage and transportation of postharvest brassica pekinensis.