Crystallization and melting behaviors of poly(p-phenylene sulfide) (PPS) in blends with poly(ethter sulfone) (PES) prepared by melt-mixing were investigated by differential scanning calorimetry (DSC). The blends showed two glass transition temperatures corresponding to PPS- and PES-rich phases, which increased with increasing PES content, indicating that PPS and PES have some compatibility. The cold crystallization temperature of the blended PPS was a Little higher than that of pure PPS. Also, the heats of crystallization and melting of the blended PPS decreased with increasing PES content;, indicating that the degree of crystallinity decreased with an increase of PES content. The isothermal crystallization studies revealed that the crystallization of PPS is accelerated by blending PPS with 10 wt % PES and further addition results in the retardation. The Avrami exponent n was about 4 independent on blend composition. The activation energy of crystallization increased by blending with PES. The equilibrium melting point decreased linearly with increasing PES content.