The present invention relates to a process for preparing powders of niobium suboxides or niobium, wherein the process comprising: mixing the niobium oxides as raw material with reducing agent, conducting a reaction at a temperature in the range of 600˜1300° C. in an atmosphere of vacuum or inert gas or hydrogen gas, leaching the reaction product to remove the residual reducing agent and the oxides of the reducing agent and other impurities, heat treating at a temperature of the range of 1000˜1600° C. in an atmosphere of vacuum or inert gas, and screening to obtain the powders of niobium suboxide or niobium of capacitor grade. According to the present invention, the niobium oxides were directly reduced into capacitor grade niobium suboxides or niobium with reducing agents which can be easily removed by mineral acids, wherein the speed of the reaction can be controlled and the reaction can directly reduce the niobium oxides into capacitor grade niobium suboxides or niobium powder. According to the present invention, the process is simple with high yield and high productivity. The products obtained have good flowability, low impurities, uniform distribution of oxygen, and have good electrical properties.