The influences of the location of mixed host material and the combination of mixed host material and guest material in EML were investigated on the performance of white organic light emitting diodes (WOLED) with double emitting layers structure. A high efficiency and high color stability device with simple structure was achieved. The maximum values of the luminance, power efficiency and current efficiency reach 29 630 cd/m², 20.84 lm/W and 33.87 cd/A, respectively. And the color coordinates (CIE1931) are (0.37±0.01, 0.44±0.01) when the voltage varies between 5~9 V.