Bulk wave reflection formulas are extended to the surface‐wave case, considering Rayleigh and Stoneley waves in terms of refracted inhomogeneous longitudinal and transversal waves, linked by the surface coupling. In this manner, a physical mechanism of second‐harmonic generation process is clearly shown. The analytical expressions and physical pictures of Rayleigh‐ and Stoneley‐wave harmonic generation have been derived in a second‐order approximation. The solution shows that the second‐harmonic surface waves have a field structure different from the fundamental ones and varying with the propagation distance. Some parameters were defined to characterize the elastic surface‐wave second‐harmonic generation efficiency. Numerical data for some isotropic materials are present. The steady‐state form of finite amplitude surface wave is described and explained by a clear physical model.