Al-Si metal matrix composites (MMCs) reinforced with 20 vol.% alumina-silicate shot fibers (Al2O3-SiO2(sf)) were fabricated by an infiltra-tion squeeze method. Pure Pr metal was added into these composites. The effect of Pr addition on the microstructure evolution of Al-Si MMCs was investigated by SEM, TEM, and EDS. Pr addition is favorable to make uniform microstructures with the modified eutectic Si crystal. PrAISi phase with high contents of Pr and Si is observed on the interface between the fiber and the matrix. The addition of Pr pro-motes interface SiO2 reduction, and SiO2 comes from the crystallization of Al2O3-SiO2 short fibers.