With the development of micro arc oxidation and the growing maturity of the industrialization, the electrolyte service life and stability attract more and more people. In this paper, the electrolyte service life was researched. Under the same technological conditions, it was found that the critical factors affecting the electrolyte service life are the single-processing area and the electrolyte volume. With prolonging the working time of the electrolyte, the gel deposition mass in the electrolyte and the initial voltage always change. The experiment indicates that the electrolyte service life will assume the curve extension when reducing the single-processing area or increasing the solution volume. To some extent, the initial voltage and gel deposition can indicate the active state of the electrolyte, and can be considered as the sign whether the electrolyte service life becomes due.