PTT[poly(trimethylene terephthalate)] fiber was annealed by passing on the plate heater to illuminate the effects of annealing on the mechanical properties and dyeability with varying the treatment temperature for 0.5 second. The apparent crystal sizes and crystallinity were increased with increases in temperature. With the increases of the temperature, the dynamic viscoelastic behaviors were analyzed to be reduction in Tmax(tanδ). The initial modulus were observed to be a small enhanced. The shrinkage in hot water were reduced. The dyeability for disperse dye enhanced dramatically, for example, a satisfactory degree of exhaustion was obtained by dyeing at 95℃ for 30 min with the PTT fibers heat treated at 180℃.