This paper on optimizing the anodised Al oxide for DNA detection by using Taguchi method. One step anodizing is carry out in the mixture electrolyte using phosphoric and oxalic acid. Control factor for this study is voltage, concentration and time. The corrosion tested to measure polarization resistance. The Taguchi methods will be optimize the anodizing parameter for DNA application. These three samples is then undergo DNA immobilization with 10µM DNA with amine-terminated group and leave it in 4h at RT. The cyclic voltammetry used to detect DNA by measure the immobilization current (Iimmo). From the result, anodized part with DNA immobilized have higher immobilized current thanpolarized part with DNA. Scanning Electron Microscope (SEM) is to observe the surface morphology of the anodized and polarize part. The result show anodized part had more particle and dispersed around than the polarize part.