Thin-film transistors (TFT) with top-gate and top-contact structure were prepared using zinc-tin-oxide (ZTO) film as the channel layer and polymethyl methacrylate (PMMA) film as the dielectric layer at low temperature (100℃), and the effect of oxygen partial pressure on the device performance was investigated during the ZTO channel layer formation process. The results show that ZTO channel layer has stable amorphous structure and high visible light transparency (average transmittance ≥89.61% in the range of 400~700nm), and increasing the oxygen partial pressure is beneficial to the improvement of visible light transparency. Hall test results show that the increase of oxygen partial pressure (from 3.5×10-2Pa to 7.5×10-2Pa) will reduce the ZTO electron carrier concentration (from 4.73×10¹⁵cm-3 to 6.11×10¹²cm-3), resulting in a reduction in the energy consumption of TFT devices based on ZTO channel layer (shown as the reduction of the off state current and the forward shift of the depletion device threshold voltage). In addition, increasing the oxygen partial pressure is also conducive to the optimization of the channel/dielectric layer interface state (that is, the subthreshold swing is reduced).