The corrosion of A3F and X70 pipeline steel by hydrogen sulfide content in the Liaohe oilfield is studied by employing potentiometric polarization curve and AC impedance technique, and the corrosion morphology of two pipeline steels is observed by the metallurgical microscope. The results show that two kinds of pipeline steels exhibit typical activation control during the electrode process. The corrosion resistance of X70 pipeline steel is significantly better than that of A3F pipeline steel, and the corrosion forms are all local corrosion accompanied by pitting.