Plastic organic light emitting diode displays suffer from residual image, which is closely connected with the hysteresis of the driving thin-film transistor in the pixels. Therefore, in researching paper, we manufactured an OLED display comprise a polyimide substrate and an amorphous indium gallium zinc oxide thin film transistor active layer. Paper proposed a solution for reducing hysteresis through oxygen partial pressure control and evaluated it using hysteresis analysis. The results showed that hysteresis is strongly dependent on the threshold voltage is settled by the oxygen partial pressure while active layer deposition of the TFT. Moreover, hysteresis decreases with increasing temperature.