The invention discloses a measuring method of an aluminum alloy CCT (Continuous Cooling Transformation) diagram, which comprises the following steps: 1. measuring data of aluminum alloy voltage and temperature along with the change of time under various cooling regimes; 2. drawing a voltage-temperature curve and a temperature-time curve in the cooling process of a sample according to the data obtained by the first step; 3. determining phase transformation points: determining the temperatures of phase transformation starting points and phase transformation ending points of the aluminum alloy sample according to the change position of the slope of the voltage-temperature curve; and 4. drawing the CCT diagram: drawing the temperature-time curve of the sample obtained at different cooling speeds to a logarithmic coordinate system, labeling the phase transformation starting points and the phase transformation ending points on corresponding temperature-time curves according to the phase transformation starting points and the phase transformation ending points determined according to the voltage-temperature curve, and connecting the phase transformation starting points and the phase transformation ending points by lines to obtain the CCT diagram of the sample alloy. The method has the advantages of strong operability, simple process, simple operation, high speed, dense acquired points, measuring material saving and higher measuring precision, fills up the blank of a measuring technology of the CCT diagram of the aluminum alloy and is suitable for scientific research units to measure the phase transformation points of the aluminum alloy and the CCT diagram.