The invention relates to a vacuum heat treatment method for nanometer powder, the nanometer powder is filled into a vacuum furnace, under the condition of not lower than 10E-2 Pa vacuum, the temperature of environment is raised to the 500-1300 DEG C at a rate of 5-20 DEG C/min and kept for 0.5-5h, and then cooled to room temperature. The vacuum heat treatment method of the invention can eliminatepowder agglomeration, remove gas absorbed on the surface of the powder, and improve nanometer sinter activity of powder, the treated powder shortens the sedimentation time greatly, thereby being advantageous for preparing massive non-cracked transparent nanometer ceramic.