The vibration of railwayballa st is a keyfact or to cause track geometrych ange and increase of track maintenance costs. So far the methods for analyzing and testing the vibration of the granular ballast have not been well formed. In this paper, a five-parameter model for analysis of the ballast vibration is established based upon the hypothesis that the load-transmission from a sleeper to the ballast approximatelyco incides with the cone distribution. The concepts of shear stiffness and shear damping of the ballast are introduced in the model in order to consider the continuityof the interlocking ballast granules. A full-scale field experiment is carried out to measure the ballast acceleration excited bymoving trains. Theoretical simulation results agree well with the measured results. Hence the proposed ballast vibration model has been validated.