Abstract: The marine flexible pipe is a multi-layer pipeline which used for gathering and transporting oil, gas and water under seawater. The area between the inner and the outer polymer material is called the annulus, and the metal material of the armor layer in the annulus is usually carbon steel. Corrosive media such as water vapor, CO2 in the transport medium of the inner pipe will penetrate into the annular area and cause corrosion of metal materials. During the design stage of the pipeline, the corrosion performance of the pipeline needs to be evaluated to verify that the corrosion resistance of the material at the end of the entire lifetime still meets the design requirements of the pipe body. According to the ASTM G111 standard, the normal corrosion tests need to consider temperature, pressure, test medium, pH, etc, but due to the low porosity in the annulus of flexible pipe, there are a large number of metallic materials in the limited corrosive medium, so the normal test method cannot truly reflect the corrosion in the annulus of flexible pipe. The purpose of this article is to explore the evaluation methods of metallic materials in the annulus of marine flexible pipe, to study the corrosion behavior of metallic materials of armor layers, and to analyze the corrosion trends of materials.