Abstract: A double-logarithmic velocity profile model(DLVPM) for tidal currents in near-bottom boundary layers is established.The DLVPM is achieved on the bases of the hydrodynamic equations for nonlinear unsteady tidal currents and the vertical distribution of Reynolds stresses,together with the Prandtl's mixing length theory and the von Karman's self-similarity hypothesis.The DLVPM is applied in the west Solent a narrow channel between the Isle of Wight and the southern mainland of England and the Xiyang estuary out of Jiangsu coastlines in eastern China.The simulated tidal current velocity profiles are compared to the observations with satisfactory results.A comparative study is then carried out to evaluate the performances of three different velocity profile models including logarithmic,logarithmic linear and DLVPM.The result shows that both friction velocity and roughness height can be better simulated using DLVPM compared to another two simulations in the two model applications.