A new kind of electric-double-layer indium-tin-oxide (ITO) thin-film transistor (TFT) is fabricated on a paper substrate by one-shadow-mask process. The channel layer can be simultaneously self-assembled between ITO source/drain electrodes by only one shadow mask during RF magnetron sputtering deposition at room temperature. Base on this, we choose microporous SiO2 with electric double layer effect as a gate dielectric, and successfully develop the ultralow-voltage oxide TFT on a paper substrate. The TFT exhibits a good performance with an ultralow operation voltage of 1.5 V, a field-effect mobility of 20.1 cm2/Vs , a subthreshold swing of 188mV/decade, and a large on-off ratio of 5× 105. The full-room-temperature oxide TFT on the paper substrate by one-shadow-mask process shows a lot of advantages, such as low operation voltage, simple device process, low cost, etc. Such a TFT is very promising for the application of low-power and portable electronic products in the future.