his paper presents the production technique of Si3N4/ SiC composite powder by carbothermic reduction of silica. The influences of process parameters, such as reaction temperature, time, original powder property, the ratio of SiO2/ C, the flowing rate of N2 and the adding amount of Si3N4, on the production properties are discussed. It has been found that the raising of reaction temperature,prolonging of reaction time, increasing of specific surface of original SiO2 powder,the ratio of SiO2 / C and the flowing rate of N2,are of advantage for the forming of Si3N4 and SiC phase.The ultrafine powder has been produced by controling each process condition at the same time.