The disclosure relates to a method of making organic light emitting diode array. A base defining a number of convexities is provided. Three of the convexities, that correspond to the same pixel unit, have different heights. A number of first electrodes are applied on the number of convexities. A number of electroluminescent layers are transfer printed on the number of first electrodes to form the number of organic light emitting layers. A patterned second insulative layer is made to cover the number of first electrodes and expose the number of organic light emitting layers. A second electrode is electrically connected to the number of organic light emitting layers.