Unidirectional silicon carbide fiber reinforced aluminum-silicate based geopolymer matrix composites(SiCf/geopolymer composites)with different fiber contents were prepared by a simple ultrasonic-assisted slurry infiltration method.The composites were exposed to air at different temperatures.The results show that the SiCf/geopolymer composites exhibit improved flexural strength and fracture toughness due to the incorporation of SiC fiber,especially for the composites reinforced by 20vol.%SiC fiber.