The effect of elastic and plastic strain on corrosion behavior of X90 pipeline steel in a simulated marine alternating dry/wet environment was investigated by means of slow strain rate tensile test, in?situ electrochemical measurement, scanning electron microscope (SEM) observation and X-ray Diffraction (XRD) test. The results indicate that in the elastic strain regime, the corrosion susceptibility of X90 pipeline steel increases with the enhancement of elastic strain, but the effect is not pronounced. In the plastic strain regime, the corrosion susceptibility of X90 pipeline steel increases significantly with the enhancement of plastic strain. The most severe surface corrosion of X90 pipeline steel occurs at a plastic strain level of 5.5%. It is attributed to the mechano-electrochemical effect of X90 pipeline steel under external stress. The corrosion mechanism is anode dissolution dominated and hydrogen evolution assisted. The result of corrosion product analysis show that strain has no significant effect on the type of corrosion products.