Owing　to　the　existence　of　high　hydrodynamic　pressure　in　heavy　traffic　conditions,　moisture　will　diffuse　quickly　into　the　asphalt　mixtures,　which　will　induce　the　adhesive　failure　of　asphalt　mixtures　and　shorten　the　service　life　of　asphalt　pavement.　This　research　aims　at　solving　the　problems　of　moisture　diffusion　and　distribution　of　asphalt　mixtures,　especially　in　heavy　traffic　conditions.　The　moisture　diffusion　paths,　moisture　distribution　and　the　susceptible　areas　of　moisture　damage　were　investigated　by　molecular　dynamics　simulations,　numerical　simulation　and　experiments.　The　slope　of　fatigue　lifetime　function　of　OGFC-13　(1.0　atm),　OGFC-13　(1.5　atm)　and　OGFC-13　(2.0　atm)　is　-4.23,　-4.22　and　-4.20,　respectively.　It　shows　that　hydrodynamic　pressure　affects　the　fatigue　lifetime　and　reduces　the　durability　of　asphalt　mixtures.　The　moisture　diffusion　path　is　three-dimensional　tortuous　curves,　and　moisture　distribution　is　related　to　air　voids　or　mixtures　types　of　asphalt　mixtures,　and　the　moisture　diffusion　coefficient　of　z-direction　is　the　biggest　in　heavy　traffic　condition.　Moreover,　the　length　of　moisture　diffusion　paths　is　more　than　the　thicknesses　of　the　asphalt　mixtures.