Coastal vegetation can function as the energy attenuator for solitary waves and the primary objective of the present study is to explore the performance of roots, stems, canopies and distribution densities on the height decay of a solitary wave passing through a vegetation belt. If the wave nonlinearity is greater than 0.11, the wave height attenuation induced by stems is not consistent with power or exponential laws. The trends of wave height decay induced by roots and stems are similar to that of pure stems when the submergence ratios are equal to 0.67. If the submergence ratios are less than 0.67 and the wave nonlinearity is not less than 0.30, the wave height attenuation under the effects of stems and canopies fits well to power or exponential laws. Under non-submerged conditions, the intensities of wave height attenuation affected by the vegetation belt decrease and the boundary effects of the vegetation belt become weaker as the distribution densities decease. Compared with roots and stems, the characteristics of solitary wave height attenuation can be efficiently influenced by canopies. In addition to the effects of roots, stems, canopies and distribution densities, the characteristics of wave height attenuation is related to the submergence ratio and solitary wave nonlinearity.