We fabricated the electrolyte-dielectric-metal (EDM) sensor on the base of AAO (anodic aluminum oxide) template with variation of the anodizing temperature. When a surface is immersed or created in an aqueous solution, a discontinuity is formed at the interface where such physicochemical variables as electrical potential and electrolyte concentration change significantly from the aqueous phase to another phase. Because of the different chemical potentials between the two phases, charge separation often occurs at the interfacial region [1]. This interfacial region, togeter with the charged surface, is usually known as the electrical double layer (EDL) [2]. The structural and electrochemical properties of AAO sensor were investigated for applications in capacitive pH sensors. To change the thickness of the AAO template, the anodizing temperature was varied from $5^{circ}C$ to $20^{circ}C$, the thickness of the AAO template invreased from 300 nm to 477 nm. The pH sensitivity of sensors with the anodizing temperature of $20^{circ}C$ showed the highest value of 56.4 mV/pH in the pH range of 3 to 11. The EDM sensor with the anodizing temperature of $20^{circ}C$ exhibited the best long-term stability of 0.037 mV/h.