Lattice　Boltzmann　method　(LBM)　is　used　to　investigate　liquid　water　transport　and　distribution　in　a　porous　gas　diffusion　layer　(GDL).　The　GDL　with　microscopic　porous　structures　is　obtained　from　three-dimensional　reconstruction　using　the　stochastic　method,　and　its　macroscopic　transport　properties　including　permeability　and　effective　diffusivity　are　numerically　predicted　which　agree　well　with　the　existing　experimental　results.　Simulation　results　show　that　liquid　water　transport　mechanism　in　the　GDL　is　capillary　fingering　and　liquid　water　pathway　is　interconnected,　which　confirms　the　previous　experimental　results　in　literature.　Further,　effects　of　GC　wettability　are　explored　and　it　is　found　out　that　a　hydrophilic　GC　leads　to　less　liquid　water　accumulated　in　the　GDL　compared　with　a　hydrophobic　GC.　In　addition,　effects　of　GDL　wettability　on　liquid　water　distribution　are　explored.　Simulation　results　show　that　PTFE　content　itself　cannot　determine　liquid　water　distribution　inside　the　GDL　and　detailed　distributions　of　hydrophobic　and　hydrophilic　regions　within　the　GDL　also　play　an　import　role.　Moreover,　a　hydrophilic　GDL　is　more　beneficial　for　reactant　transport　than　a　hydrophobic　GDL　if　liquid　water　presents　as　separated　droplets　or　films　in　the　GDL.