In this study, the effect of aging and first heater temperature on the physical properties of polybutylene terephthalate false‐twist textured yarn including mechanical properties (tenacity, breaking elongation) and crimp properties (crimp contraction, crimp modulus, and crimp stability) are studied. The as‐spun fibers were produced at melt spinning temperature of 257°C and winding speed of 2850 m/min. The as‐spun yarns were subjected to draw‐texturing processes in 160°C‐200°C with interval of 10°C. Fiber structure and physical properties of yarn samples were measured and evaluated. The results showed that as the first heater temperature increases, the value of tenacity and crimp properties of yarns increases while the breaking elongation and shrinkage values decrease. In addition, properties of aging yarns textured after 80 days was stable and this a positive point. It also showed the storage advantage of polybutylene terephthalate textured yarns in comparison with PP and PET. In addition, the storage of POY yarn had no effect on the properties of the textured yarn at 190°C.