In view of the failure problem of aluminum electrolytic capacitors in storage environment, electrolytic
capacitors were investigated through humid heat test. The influence of hygrothermal environment on the surface state and electric performance of aluminum electrolytic capacitors was evaluated. And the failure phenomena were observed and analyzed. The results showed that corrosion of lead and molds of rubber plug occurred on aluminum electrolytic capacitors in hygrothermal environment. Temperature had great effect on the storage reliability of aluminum electrolytic capacitors. Corrosion rate of lead was accelerated when the temperature was higher than 40. The suitable temperature for molds growth was 30. No mold was found in the rubber plug when temperature was higher than 30. The capacity and leakage current of aluminum electrolytic capacitors increased with storage time, which was caused by the corrosion of aluminum oxide film on anode foil.