The growth process of tantalum capacitor oxide film for 0603 size was investigated. The main process parameters of dielectric film Ta2O5 quality including formation fluid type, formation liquid concentration, current density and constant voltage time were employed to carry out experiments. At last DC leakage current of wet measure was collected, and through comparative experiments the best process parameters of the oxidation film growth were obtained. In conclusion, the best process parameters are 0.2% (volume ratio) nitric acid solution, 40 mA/g current density and 5 h constant voltage time. Through the best process parameters, the oxidation film quality can be improved greatly. Finally, leakage current is very small and comes to 0.036 μA