Abstract: In view of hemp fiber inherent drawbacks such as rigidity,poor prolongation and irreversible deformation under external strain,the treatment of liquid ammonia is applied to improve its poor physical properties.The article studies liquid ammonia effect on hemp fiber property and analyzes the result of experiments.It is found that after the liquid ammonia treatment,hemp fiber′s density decreases from 1.537 7 g/cm3to 1.531 9 g/cm3;the percent of compression and compression elasticity ascends;static and dynamic frictional coefficient declines.The study also reveals that the liquid ammonia treatment has rendered better dyeability to the fiber with little effect on its strength.