O'-SiAlON/SiC ecomaterials were synthesized by using the Yangtze River sand that containing abundant Si and Al elements as the major raw material with minor additives through the carbothermal reduction nitridation route combined with colloidal process. This study realized the conversion of ecomaterials from non-traditional resources, Yangtze River sand. Orthogonal design was adopted to optimize the colloidal process parameters. The green compact with the largest bulk density was obtained when the solid volume loading is 50%, the addition mass fraction of SL is 0.8%, the addition mass fraction of CMC is 0.05%, the ball milling time is 10 h, the pH value is 9 and particle size distribution is multi-peak in the colloidal process. The effects of reduction agent, flowing rate of N2, sintering temperature during carbothermal reduction nitridation process on the microstructure of as-fabricated SiAlON materials were explored. The XRD results indicated that when sintering temperature is 1450°C, maintaining time is 6 h, flowing rate of N2 is 1.0 L/min and carbon black is selected as reduction agent, O-SiAlON/SiC composites was successfully synthesized. The SEM images showed the densificated microstructure and uniform grains with the short column shape.