The non-isothermal crystallization kinetics of polyphenylene sulfide (PPS) and its blends with polyaryletherketone-bearing phthalidylidene group (PEK-C) was investigated by differential scanning calorimetry. The experimental data were evaluated quantitatively. It was found that the blend of PPS incorporating 10 wt% PEK-C has the maximum crystallizability. The mechanism involved in the effect of PEK-C on PPS crystallization behaviour is proposed.