Abstract: Fatigue tests were carried out to investigate the fatigue properties and corrosion fatigue properties in seawater of 0Cr16Ni5Mo stainless steel. Fractographic analysis was conducted through optical microscope and scanning electron microscope. The results show that σ_-1 、 σ_-1SCC and τ_-1 of 0Cr16Ni5Mo was 550MPa、408MPa and 285MPa respectively,the relationship among σ_-1, τ_-1, σ_b and σ_0.2 conform to Ojeng formula. The fractographic characteristics varied according to test conditions, of which fractograpy of rotary bending fatigue exhibited normal fracture features, propagation of torsional fatigue constituted no distinct fatigue strips, this was attributed to complicated stress state. Fatigue fracture in seawater was characterized by multi-crack source on specimen surface. The stress concentration at the tip of the crack speeded up the crack propagation, which resulted in the decrease of corrosive fatigue strength. The mechanisms of the crack propagation and the final fracture correspond with the well-known fatigue failure mechanisms.