The present invention provides a method of compensating AMOLED power supply voltage drop, comprising: step 1, measuring a brightness value L of each light-emitting element line of a panel by starting from a COF end of the AMOLED; step 2, drawing a brightness variation curve of the each light-emitting element line caused by IR Drop according to the brightness value L of the each light-emitting element line measured in the step 1; step 3, calculating a voltage value for compensation of every two adjacent light-emitting elements from difference values between the brightnesses of every two adjacent light-emitting elements according to a ratio conversion between a brightness difference ΔL and a voltage difference ΔV, i.e. ΔV=α·ΔL, wherein α is a scaling factor; step 4, making no compensation to a data voltage of the first light-emitting element line, and adding the first compensation value ΔV1 to a data voltage of the second light-emitting element line, and adding a sum (ΔV1+ΔV2) of the first and the second compensation value to a data voltage of a third light-emitting element line and so on to the last light-emitting element line when a sequence controller transmits data voltage signals for showing images. The method can solve the issue of uneven brightness caused by IR Drop in a large scale AMOLED display device.