The non-isothermal crystallization and subsequent melting behaviors of poly(trimethylene terephthalate), (PTT)/Vectra A950, (VA) blends with different VA contents were studied by differential scanning calorimetry. The effects of VA on the non-isothermal crystallization kinetics of PTT were discussed based on the Ozawa model. It was found that VA has a nucleation effect on PTT crystallization. The triple melting endotherms were found in the subsequent melting thermograms. The blends are clearly immiscible as verified by the unchanged Tg and morphological results.