Abstract: Epoxy and epoxy-based components have been extensively used in marine industry due to their excellent performance. When exposed to moist environment, the matrix of such materials absorbs significant amount of water and damages are caused including warpage, expansion and other deformations. In this study, weight analysis experiment were carried out and fibre Bragg grating (FBG) sensors were used to monitor the effects of moisture absorption. The maximum water absorption, water diffusion coefficient, and coefficients of moisture expansion were determined thereafter. Numerical simulation was then built accordingly by finite element method to predict the evolution of moisture absorption and the stress field developed in the epoxy resin. Finally, the simulation results were compared with the experimental ones by phase-shift digital photoelastic method and good agreement is achieved. The shearing stresses in the resin show the trend of initial increase and later decline during the course of water absorption.