According to a method for preparing a UO2 mixture powder for nuclear fuel manufacturing, of the present invention, mixing time is short, and degrees of mixing and homogeneity of a prepared UO2 mixture powder are excellent. The present invention relates to a method for preparing a UO2 mixture powder for nuclear fuel manufacturing, and provides a method for preparing a UO2 mixture powder for nuclear fuel manufacturing, comprising the steps of: (a) weighing and sieving, by means of an automatic injection device, a UO2 powder, a porogen and a lubricant, and injecting same into a UC container; and (b) mixing the UO2 powder, the porogen and the lubricant by means of an IBC blender.