The phase morphology and mechanical properties of melt compounded polycarbonate (PC)/acrylonitrile-butadiene-styrene(ABS) blends were investigated by changing injection molding conditions. Upon increasing injection or mold temperature, significant coalescence of dispersed phases was occurred, which also resulted in considerable reduction in blend mechanical properties. It is considered that the reduced melt viscosities of component polymers at elevated temperatures are responsible for increased coalescence by facilitating the draining process of the matrix film intervened between domains. In practice, it is important to keep the critical injection and mold temperatures in injection molding process of multiphase PC/ABS blends.