The process control of anodization has been a hot topic for a long time. In this study, the addition of phosphoric acid to the traditional electrolyte changed the ion distribution on the reaction interface and the composition of the anion contamination layer so as to achieve the slowing down effect on anodization, the mechanism and theoretical model of which are also given in this paper. TiO2 is a common material in photoelectrocatalysis, but there are few studies on the photoelectrochemical performance of TiO2 nanotube arrays. The stability and rapidity of the photoelectrochemical response of TiO2 nanotube arrays prepared in phosphoric acid containing an electrolyte were effectively optimized in this study.