The present disclosure provides a backlight compensation method, device and system, and a storage medium. The method is used to compensate brightness of a plurality of mini-LEDs in a backlight unit, where the plurality of mini-LEDs include M rows and N columns, and both M and N are positive integers greater than 1, and the method includes: acquiring a control signal for controlling the brightness of the backlight unit, and acquiring a row compensation value corresponding to mini-LEDs in each row and a column compensation value corresponding to mini-LEDs in each column; compensating the mini-LEDs in each row and the mini-LEDs in each column according to the row compensation value and the column compensation value, to obtain a compensated control signal; and controlling the brightness of the backlight unit according to the compensated control signal.