In this paper, high-speed photography was used to investigate the intrinsic dynamics of subharmonious surface wave in a vertical vibrated and idealized bidimensional granular layer. Using the high-speed photography, velocity fields of the granular layer at different stages through two cycles were obtained, which show the continuous particle motions during a cycle. From the velocity fields, a crystal structure in the wave-hollow was observed, which is reported for the first time. Furthermore, quantitative results of kinetic energy distribution in the layer were calculated, which shows temporal correspondence with the evolution of the wave pattern.