Abstract: This is a paper in the field of mineral materials. Fly ash (-2.6 μm) was used as raw material and calcined in muffle furnace at 815 ℃ for 2 h to obtain the calcined fly ash. The micro-morphology, EDS spectrum, particle size, infrared spectrum, phase composition and specific surface area-aperture of fly ash and calcined fly ash were characterized by SEM, EDS, XRF, FTIR, XRD and BET. The nylon 6/calcined fly ash composite was prepared by filling nylon 6 with 5% calcined fly ash, the tensile section of pure nylon 6 and the composite was analyzed by scanning electron microscope, and the mechanical properties, melting index and heat distortion temperature of the composite were tested. The results show that the calcination has little effect on the structure of fly ash, just remove the carbon of surface; Calcined fly ash filling in nylon 6 will not cause internal stress; Compared with the pure nylon 6, the nylon 6/calcined fly ash composite has significantly improved properties except the impact strength and melt index, in which the tensile strength, bending strength, bending modulus, bending modulus and heat distortion temperature are increased by 7.7 MPa, 26.9 MPa, 284 MPa and 46.2 ℃, respectively.