Abstract: The effects of temperature and tension of heat treatments on the structure and mechanical properties of PTT fibers were investigated through SEM observation, and testing of the tensile and the rate of resilient-elasticity recovery. The results of the experiment show that drawing at 120～ 140 ℃ will damage the structure of PTT fibers and result in a drop in deformation resistance and stretch recovery, while proper drawing at the temperature about 160 ℃ will improve the internal structure of PTT fibers and enhance the deformation resistance, strength and stretch recovery. The heat-setting of PTT fabrics at the temperature about 160 ℃ can maintain and optimize high elasticity of PTT fibers.