The invention discloses a hydrogen separation alloy critical hydrogen embrittlement characterization method and relates to the research field of hydrogen permeation performance of hydrogen separation alloy, aiming to solve the problem that a hydrogen separation alloy critical hydrogen embrittlement characterization method is absent at present. The hydrogen separation alloy critical hydrogen embrittlement characterization method includes heating hydrogen separation alloy in a vacuum state, and feeding hydrogen into two sides of the hydrogen separation alloy; keeping a specific pressure difference between the two sides of the hydrogen separation alloy, and gradually cooling the hydrogen separation alloy at a constant temperature decrease rate until hydrogen embrittlement occurs or the temperature decreases to 20-25 DEG C; recording hydrogen permeation flow, time and temperature of the cooling process; obtaining a relationship curve between the hydrogen permeation flow and the temperature of the hydrogen separation alloy at a specific pressure by combining pressure according to the temperature, the time and the hydrogen permeation flow of the cooling process, and characterizing the hydrogen separation alloy critical hydrogen embrittlement through the relationship curve between the hydrogen permeation flow and the temperature. The hydrogen separation alloy critical hydrogen embrittlement characterization method is applicable to the research field of the hydrogen permeation performance of the hydrogen separation alloy.