The performance of OLED devices(ITO/PVK/FIrPic∶SimCP/TPBi/LiF/Al)was studied by making modification of ITO surface with bromoacetic acid and 2,4-Dichlorophenoxyacetic acid, respectively. The results show that, compared with the devices without organic acid modification, the maximum brightness of the device increases from 673.4 to 1875.2cd/m2, while the turn-on voltage of the device reduces from 6.2 to 5.3V. It is considered that the organic acids can change the surface energy and the work function of ITO. On the one hand, it changes the contact performance of the ITO and the subsequent film, influencing the subsequent coating film; on the other hand, it effectively reduces the barrier between the ITO and organic layer, improving the carrier injection. This method is simple and effective in reducing the hole injection barrier and proving the contact performance of the ITO and the subsequent film, which plays a certain role in promoting the devices’ performance.