Abstract: The research on surface structure and voice mechanism of singing sand has achieved certain results at present.Some researchers think that the sound of singing sand is mainly related to the resonance cavity, which is made up of the porous structure on the surface of the natural singing sand grains.The resonance cavity is the key of the voice of singing sand, moreover, the resonance mechanism is similar to the Helmholtz resonance cavity.Based on the analysis of the natural environment and the observation to surface morphological structures of the singing sand in Dunhuang under the scanning electrical microscope, the study about the genetic types of the resonance cavities had been conducted on a comprehensive discussion.The results show that the unique natural environment of Mingsha mountain is the natural resonant tank, and it is mainly affected by geomorphology; Moreover, porous physical structures are widely distributed over the singing sand surface, and its surface morphology is diverse, then the various porous structures can constitute resonance cavities themselves, which are mainly influenced by their physical and chemical functions, or both of the two effects.

Key words: singing sand, Dunhuang, resonant tank, surface morphological structures, genetic types