Abstract: The erosion behavior of N80 oil well tube steel in 3.5% NaCl solution was studied by weightlessness method and electrochemical test. The results show that the mass loss rate of N80 steel unchanged and then increased with increasing the stirring speed. The self-corrosion current density of N80 steel during erosion was significantly greater than that during immersion corrosion under the same times. The self-corrosion current density increased with extensing the immersion time, increased and then decreased with extensing the erosion time, and increased with increasing the dissolved oxygen. The corrosion effect of fluid on N80 steel in the early stage of erosion was dominant, and the impact of fluid was dominant in the middle and late stages. With extensing the erosion time, the corrosion products on the surface of N80 steel increased, the degree of plastic deformation at the edge of the corrosion pit increased, shape of the corrosion pit gradually changed from circular to elliptical, and the corrosion rate decreased. The surface hardness of N80 steel after erosion for 1 h was lower than that of the uneroded, and after erosion for 2 h, the hardness of N80 steel was higher than that of the uneroded due to the formation of a hardened layer on the surface of N80 steel.