In this article, the phase morphology and mechanical properties of poly (trimethylene terephthalate)/maleinized poly (octene-ethylene) copolymer blends are studied by using scanning electron microscopy (SEM), polarized optical microscopy (POM), universal material tester and charpy impact tester. The results suggest that the crystal size of the blends decreases obviously and POE component is partly served as nucleating agent for the crystallization of PTT. PTT and POE have good compatibility in blends because the dispersed phase of POE has even dispersion in blends when POE content is lower than 5%; however, the dispersion state of POE becomes poor when POE content is larger than 5%. The impact strength increases to maximum when the POE content is about 4 %. The tensile strength gets to maximum when POE content is 1-2 %.