A voltage drop compensation system and method for a power supply inside a display panel, to solve technical problems of poor uniformity of screen brightness and high power consumption of the whole screen due to voltage drop of the power supply inside the display panel. The voltage drop compensation system includes a voltage detection circuit and a voltage compensation circuit, where the voltage detection circuit is configured to detect an ELVDD voltage of pixel units in each row; and the voltage compensation circuit is configured to compensate a data voltage of pixel units in each row based on a detected ELVDD voltage.