The invention discloses a method for synthesizing gamma-ALON powder at low temperature on the basis of a sol-gel technology. The method comprises the steps that aluminum isopropoxide and nanometer carbon black are used as raw materials, tetrahydrofuran is used as a stabilizing agent, PEG is used as a dispersing agent, and a precursor is obtained through an alkoxide hydrolysis reaction; the precursor is placed in a standing mode, dried, ground and screened, treatment is performed under the nitrogen protection condition of 600-900 DEG C for 0.5-1 h, heat preservation is performed under the condition that the temperature is 1650-1700 DEG C and the nitrogen flow is 0.5 L/min for 2 h, carbon is removed in air at the temperature of 600-800 DEG C after natural cooling in nitrogen is performed, finally, the product is crushed after being subjected to ball milling, and single-phase AlON powder is obtained, wherein the median particle diameter is 440 nm, and size distribution is uniform. By the adoption of the method, the single-phase AlON powder can be synthesized at low temperature, the adopted raw materials are low in cost, and the production cost is low.