Abstract: The 25CrMo steel for making the L80 anti-H₂S corrosion oil casing is designed and developed by means of the EAF-LF-VD-CC clean steel-making technology，and adding Ni and Ti to the chemical composition of the Cr-Mo steel.Relevant statistical analysis shows that the 25CrMo steel has excellent physical quality，featuring high cleanness，low harmful element contents，fine grain and homogeneous microstructure and good surface quality，etc.The said steel als>o possesses outstanding H₂S-corrosion resistance，being suitable for service under operation environment with P_H2S100 kPa.The L80 anti-H₂S corrosion oil casing as made of the said steel is in possession of mechanical properties up to the customer specified requirements.