Abstract The non-isothermal crystallization behavior of isotactic polypropylene/ethylene-octene blends under atmospheric pressure and high pressure has been systematically investigated by differential scanning calorimetry (DSC) and PVT. The apparent incubation period (∆ t i) and the apparent total crystallization period (∆ t c) were used to characterize the crystallization behavior of the blends. At low POE content, the addition of POE decreases the ∆ t i and ∆ t c of PP in blends; however, at high POE content, the addition of POE decreases the mobility of PP segments and increases ∆ t i and ∆ t c of PP in blends. The pressure dependence of the crystallization temperature of PP/POE blends shows a linear relationship. The melting temperature of blends crystallized under high pressure is significantly lower than that under atmospheric pressure. With increasing POE content, the melting peak of blends crystallized under high pressure shifts toward higher temperature, in contrast to that under atmospheric pressure.