7xxx aluminium alloys are the most widely used materials in the aircraft structural application due to their high strength, low density and low production cost. However, 7xxx aluminium alloys still suffer from the hydrogen embrittlement which can decrease their service duration and result in the fracture. The aim of this project is to provide an understanding on the hydrogen diffusion in 7xxx aluminium alloys. The mechanisms of hydrogen penetration will be studied by changing alloy composition and processing parameters. The evolution of microstructures, crystalline defects and chemical segregation in 7xxx aluminium alloys will also be studied via using the phase-field modelling method and Calphad modelling method. The chemical distribution around grain boundary zones will be detected by TEM or APT. This understanding will be used to provide some related information or references for hydrogen management and life estimation of 7xxx aluminium alloys during the manufacturing and serving processes.