Abstract: KES was used to test the elastic extension,elastic recovery,plastic deformation and fatigue resistance of three kinds of fabrics made from PTT staple fiber,DTY and PTT/PET bicomponent fiber respectively and they were compared with those of urethane elastic fiber fabric and the common chemical fiber fabrics(PET and nylon).It is found that the elastic elongation of all kinds of PTT fabric is longer than that of common chemical fiber fabrics,but less than that of urethane elastic fiber fabric;under low load condition,the PTT fabrics exhibit lower recovery and higher plastic deformation than the common chemical fiber fabrics;among the three kinds of PTT fabrics,PTT/PET fabric shows the maximum elastic elongation and the best stretch recovery,while PTT staple fiber fabric shows the lowest stretch recovery and highest plastic deformation.