Model pparameters such as friction factor and eddy viscosity in the Shiono & Knight method (SKM) are considered through experimental data obtained from a vegetated open channel. The experiment was conducted in a rectangular open channel with cylindrical rods as vegetation. Velocity, Reynolds stresses and boundary shear stress were measured with Acoustic Doppler Velocimetry (ADV) and a Preston tube respectively. Both friction factor and eddy viscosity were calculated using the measured data and found to be not constant in the shear layer generated by rods. The analytical solutions of SKM to predict velocity and boundary shear stress currently in use were based on the constant assumption of these parameters. In this paper a new analytical solution was derived by taking into a variation of these parameters account and was also verified with the experimental data. This solution was also applied to flow in compound channel with vegetation. The new solution gives a good prediction of the lateral distribution of depth-averaged velocity and boundary shear stress in vegetated channels, and it predicts the boundary shear stress better than that of the original solution without considering the secondary flow term in particular.