Mesoscale lattice network model, in which concrete was treated as a three phase composite material consisting of coarse aggregate, hardened cement mortar and interfacial transition zone（ITZ） between the aggregate and the mortar matrix, was developed to analyze water transport process in concrete. Based on the unsaturated flow theory and the cubic law of water transport in a single crack, the model of water transport coefficient in cracks was built up to numerically simulate the relative water content distribution in cracked concrete. By comparison with experimental results it is shown that the model proposed is feasible to predict the relative water content of concrete and the mesoscale modeling on water transport in cracked concrete is accurate.