The work aims to study the erosion-corrosion (E-C) resistance of epoxy resin/Q235 steel system in flowing seawater containing sand. The erosion corrosion test of epoxy resin/Q235 steel system with different velocity and sand content was carried out by using the rotary E-C test device. The corrosion behavior of the system after E-C was studied by surface observation, electrochemical test and Scanning Kelvin Probe (SKP) technique. The computational fluid dynamics (CFD) method was used to simulate the flow field and sand distribution. The results show that the sand particles at high speed continuously impact the surface of the coating and results in surface damage. After the coating is damaged, the substrate is in direct contact with the seawater, which causes the substrate corrosion, and further damages the coating. The coating damages when the eroding velocity is between 5 m/s and 6 m/s. The bottom of the coating is corroded and connected into pieces, and forms sheet corrosion products. There are long cracks on the surface of corrosion products. Moreover, the surface of the sample is partially damaged as the sand content reaches 1.5wt%. The E-C form is mainly isolated corrosion pits. With the increase of corrosion time, the anode area becomes wider and the cathode area moves outward. The corrosion area expands gradually, forming corrosion channel, and as a result, causes extensive corrosion under the coating. The coating damage is more sensitive to the flowing rate as compared with the sand content.