HfTaO-based MOS capacitors with different top electrode (Ag、Au、Pt) were successfully fabricated by dual ion beam sputtering deposition (DIBSD). We presented the effect of different metal gate on the capacity, flat band voltage shift, leakage current and conduction mechanism. It has been found that the Pt-electrode capacitor exhibited the highest accumulation capacitance. In addition, the largest hysteresis loop in Pt/HfTaO/Si capacitor during the forward-and-reverse voltage sweeping from +2.5V to -2.5V was observed. The result indicates the presence of a large amount of fixed charges or oxygen vacancies exist in interface Pt/HfTaO, which is consistent with the prediction from Qf results. It is proved that even though Eot of the Pt-electrode capacitor is lower than that of the Ag, Au-electroded, and that of leakage current still has the smallest value at a high electric field due to Pt with a high enough work function Φms(Pt)=5.65eV.