Using mixed acid as corrosive liquid to corrode the grain boundaries of ceramic dielectric layer with SEM to observe microstructure, The test results show that the type and concentration of corrosion solution, corrosion time and temperature have significant effects on the corrosion effect. And the most suitable corrosion conditions were: hydrofluoric acid-nitric acid system, configure 2 mL of hydrofluoric acid and 5 mL of nitric acid into a 100 mL solution; the corrosion period of Class2(BaTiO3) ceramics under room temp. of 25 ℃ was 50 s, while Class 1((Sr,Ca)(Zr,Ti)O3) was 15 s.