Abstract: The development of high-performance ionic gel can significantly promote the flexible electronic devices. In this study, an environmentally friendly cellulose-based ionic gel (CGel) had been designed based on the heating-cooling process, where the natural cellulose functioned as the gel framework, and the ionic liquid worked as the conductive material. In the CGel, the cellulose possesses a 3D porous structure, which can effectively adsorb and reserve the ionic liquid. The CGel presents high modules (G′>G″), superior transparency of 88% and conductivity of 2.2 mS/cm, as well as desirable flexibility. In addition, the CGel system features a recycled and reproductive character based on a hot-temperature heating and cooling gelation process. More interestingly, the cellulose-based gel is extremely sensitive to the water molecules, where the conductivity of the CGel features a positive relationship with the humidity, leading to a promising potential for real-time monitoring the environmental humidity and human skin conditions.