During the use of flexible risers, pressure gradient driven internal acidic gas (CO2, H2S, gas phase water) permeates through the lining layer and enters the annulus, forming a corrosive environment that will seriously affect the service life. At present, material permeation tests, riser prototype permeation tests and numerical simulations have been carried out to predict the annulus permeation of flexible risers and to improve the material barrier performance from the perspective of mass transfer by preparing nanocomposites. However, flexible riser permeation is a coupled process of heat and mass transfer, and in order to retard the flexible riser permeation behavior, this paper analyzes the factors influencing the flexible riser permeation and reviews the research progress of mass and heat transfer behavior of nanocomposites. The gas permeation behavior of the nanocomposite flexible riser is analyzed by using the flexible riser annular permeation prediction software with a 6-in. flexible riser as research object. The results show that the changes of diffusion coefficient and thermal conductivity of the liner material affect the riser permeation; the decrease of diffusion coefficient and thermal conductivity can reduce the flexible riser permeation; when the decrease of diffusion coefficient and the increase of thermal conductivity are the same, the flexible riser permeation rate is basically unchanged, and the research results can provide reference for the modification of the flexible riser liner material.