In order to improve the mechanical properties, crystallization behavior and processing viscosity of the poly(trimethylene terephthalate) (PTT), maleinized poly(octene-ethylene) (POE) and organomontmorillonite (OMMT) were used to prepare nanocomposites of PTT/POE/OMMT by melt blending method, and their morphology and properties were investigated in detail. The results suggest that some of the OMMTs are peeled off and the nanosheets are dispersed evenly in the polymer matrix. The nanocomposites have higher melt viscosity with increasing OMMT content due to the interaction between OMMTs and polymers, which is favorable for improving the processing property of the material. The nanocomposite with 2 wt% OMMT has the largest tensile and impact strength. The elastic modulus of the glassy nanocomposite increases, and the glass transition temperature first slightly decreases and then increases with increasing OMMT content. The nanocomposites form smaller or imperfect microcrystallites with lower melting point and the nanocomposites have increased crystallization rate because of the effective nucleation agent of OMMT. However, the