Abstract: The long non-linear waves in shallow water propagation is studied experimentally and numerically.Fnrst order and second order incident boundary condition on fixed incident boundary are derived for numerical simulations,based on the cnoidal motion of wave maker paddle,which shows that the prediction with second order incident boundary condition is more accurate than the prediction with first order incident boundary condition.The Fourier analysis of measured and computed time history of water elevations with second order incident boundary condition shows that there is periodic transformation for different component of waves along wave flume,while no periodic transformation with first order incident boundary condition.