Five kinds of organic quantum well structured light-emitting devices are fabricated, and their electrical characteristics are studied. The effects of quantum well period number and barrier thickness on device performance are analyzed. Experimental results show that appropriate cycle quantum well structured devices have higher brightness and current efficiency than the traditional three-layer devices. That is because of the limitation effect of quantum well structure on electrons and holes,and the structure of this kind could improve the composite probability of excitons in the light-emitting layer,thereby increasing brightness and efficiency of OLED. There is also an effect on brightness and efficiency when the potential well layer thickness of quantum well structured device is changed. Consequently,the adoption of appropriate potential well layer thickness can also improve the brightness and the efficiency of the device.