Abstract: To evaluate the practicability of hollow fiber polypropylene membrane modified by cysteine(PP-g-Cys),its thermal stability and mechanical properties were analyzed by dynamic mechanical thermal analysis,thermogravimetry and tensile test.The results show ultraviolet irradiation has little effect on the mechanical property of polypropylene hollow fiber membrane in N2,whereas it decreases the break strength of the membrane in atmosphere.The elongation at break of PP-g-Cys descends with the increase of grafting degree.And the glass transition temperature(Tg) of PP-g-Cys drops,that is,the macromolecule becomes softer.The cysteine grafted side chain on PP-g-Cys membrane is thermally unstable,the its highest application temperature of the modified membrane is 212.4℃and 191.5℃in N2and O2respectively.