An organic light emitting diode (OLED) illumination compensating method and device includes obtaining a plurality of first brightness values and corresponding actual driving voltage values; establishing a mapping relationship between brightness values and actual driving voltage values based on the plurality of first brightness values and the plurality of actual driving voltage values; obtaining target brightness values of the plurality of pixel units, and obtaining target driving voltage values of the plurality of pixel units by way of calculation based on the mapping relationship and the target brightness values; compensating for brightness of the plurality of pixel units based on the target driving voltage values and current actual driving voltage values.