Abstract: A multi-ion potential sensor is disclosed. The multi-ion potential sensor comprises a substrate, a conductive layer, an isolation layer, a tin oxide (SnO2) layer and a selective layer. The conductive layer comprises a plurality of independent conductive areas, wherein every conductive area comprises a readout area, a transmissive area and a sensing area, and the transmissive area of every conductive area is packaged by the isolation layer. The tin oxide layer comprises a plurality of independent tin oxide areas, wherein every tin oxide area is deposited on the sensing area, and the selective layer comprises a plurality of independent selective areas, wherein every selective area is set on the tin oxide area. The multi-ion potential sensor has various advantages, such as good sensitivity, low cost, simplicity, disposable, portable and data acquisition by a computer for different applications.