Abstract: The morphology,composition and hot deformation of oxide-sulfide duplex inclusions in resulfurized gear steel DIN 18CrNiMo7-6 were studied by metallographic examination,scanning electron microscopy (SEM) and electron spectroscopy analysis.The results show that the hot deformability of the oxide-sulfide duplex inclusions decreases with the increase of calcium content in the peripheral sulfides until the atom fraction of about 5.0%.Increasing the area ratio of the core oxides with high melting point makes the duplex inclusions less susceptible to deformation,while the oxides with low melting point have not obvious effect on it.