In this article, butyl rubber (IIR) was blended with ethylene-vinyl acetate copolymer (EVA) through a molten method. The crystal structure, morphology, crystallization and segmental dynamics were characterized. The crystal structure test indicated that IIR had no influence on the crystal form of EVA. Furthermore, the morphology showed that the blends changed from sea-island to a co-continuous structure. Moreover, the non-isothermal crystallization kinetics given by Mo’s model showed that the rate of crystallization became fast as the content of EVA increased. In addition, the segmental dynamics characterization illustrated that EVA suppressed the molecular motions of IIR to a different degree. Longer units were more influenced than shorter units. It was also found that both crystallization and molecular dynamics had a close relationship with the morphology.