///In this paper, a periodic layered medium model with different thickness for each layer was constructed by infusing one material into another and then transmission observation to the model was conducted by using sources with 1, 0.6, 0.2 MHz as dominant frequencies respectively; through recording the waveform variation during the propagation in the vertical layered media, the influence of different periodic layer thickness d to wavelength λ and velocity V, and the relationship between V and λ/d was analyzed. The results showed that when the volume of each material is close to each other, V and λ/d are related in vertical direction, that is, λ/d is less than 1, V is consistent with average velocity; when λ/d is between 8 to 11, V drops rapidly, the minimum of V is close to the effective medium estimated velocity in the periodic layered medium. When λ/d is close to 1 or 8, it is turning point for velocity variation, at the same time the energy of the transmitted wave severely attenuated.