This work studies the effects of acid concentration and current density on etching morphology, microstructure and static capacity of the aluminum foils used in high-voltage electrolytic capacitors. The behavior associated with electrochemical etching was investigated with a potentiostat. The aluminum etching type of DC etching is greatly influenced by the etching potential. The static capacity increased to 0.65 uF/cm2 with 540 V forming voltage by optimization of the etching parameters used in this work.