In this paper, the atmospheric pressure oxygen plasma was used to increase the work function of Ag thin films surface. But Ag thin films was generally not considered as an ideal bottom anode for T-OLED due to its rather low work function (approximately 4.2 eV). Using plasma treatment, the work function of Ag films was increased up to 4.84 eV at the plasma treatment time of between 60 and 90 s. The KPFM and Nano-indenter method analyzed and measured the work function of nano-distribution and nano-mechanical properties of Ag films surface. From the KPFM and Nano-indenter analysis, the stresses of Ag thin films were generated by induced oxygen radicals during the plasma treatment, and the work function of Ag thin film on nano-surface also changed by induce stress. It is can be explained that the nanosurface of thin-film would be generated the stress during the plasma treatment and the induced stress could change the surface property due to increase its volume. It is plausible that the induced stress was accelerated the production of AgO or AgO2 and excessive volume expansion of AgO2 could damage the surface.