A potentiometric glucose biosensor based on a SnO2/ITO/PET substrate is presented in this study. The sensing membrane of SnO2 is coated on ITO/PET substrate by utilized radio frequency (RF)-sputtering method of semiconductor fabrication. The potentiometric glucose biosensor is established on an FET-type pH sensor. Therein, the glucose oxidase (GOD) and chitosan/multi-wall carbon nano-tubes (chitosan/MWCNTs) are immobilized by 3-glycidoxypropyl trimethoxysilane (3-GPTS). Finally, the drift characteristic and calibration curve of the potentiometric pH sensor and potentiometric glucose biosensor is discussed in the following article. We find the nonideal effect of device reduced significantly, due to the coating of SnO2 thin film.