White organic light emitting devices with the structure of ITO/ MeO-TAD (15 nm) /NPBX(40 nm) /DPVBi(x nm)/ Rubrene(0.3 nm)/DPVBi (20-x) nm /BCP(5 nm) / Alq3 (30 nm) /LiF(0.5 nm) /Al. High-mobility MeO-TAD is added into the region between ITO and NPBX to increase hole injection and transport. The BCP layer was used as the hole blocking layer .In the meanwhile, an effective carrier balance (number of holes is equal to number of electrons) between holes and electrons is considered to be one of the most important factors for improving OLEDs. During the experiment, by modulating the thickness of DPVBi , we can control hole injection and electrons transport to make the carriers reach a high-level balance. The maximum current efﬁciency was 1.22 cd/A.