The work aims to improve steam oxidation resistance of S30432 steel. Surface shot peening was applied to inside surface of S30432 steel. Steam oxidation experiment was performed to shot-peened and untreated S30432 steel tubes steam oxidation experimental platform, and oxidation behavior of two samples was comparatively studied at 650 ℃ in steam. Weight gain changes of the samples were measured with analytical balance. Surface morphology and microstructure of oxide scale were observed with scanning electron microscope. The untreated S30432 steel exhibited parabolic oxidation kinetics while the treated S30432 steel exhibited complete oxidation resistance. Fe-riched oxide fromed on the surface of the untreated S30432 sample, and the scale thickened quickly due to instability oxidation after nearly 200 h and was 13 μm after 500 h. The treated sample had very thin (about 0.5 μm thick) Cr-enriched scale which exhibited good protective effects. Shot peening treatment can significantly improve steam oxidation resistance of S30432 steel, and generate complete Cr-enriched scale on the surface rapidly by inhibiting instability oxidation.