In order to study the dynamic response of the drum of vibratory roller during different compaction stages， the drum-subgrade coupling dynamic model describing the motion of the drum is established， by introducing state vector σ for the interaction between drum and subgrade， and plastic parameter ε for the elastic-plastic state of subgrade. Based on the model， the time history，phase diagram， frequency spectrum， Poincaré map and bifurcation diagram of the drum’s response are obtained by numerical integration method， and the dynamic responses of the drum associated with various plastic parameters are analyzed. The results show that the drum of vibratory roller exhibits a dynamic evolution of “single period motion?period doubling motion?chaos motion”. In the single period motion， the drum is in constant contact or periodic loss of contact relative to the subgrade， while in the period doubling and chaos motion， the phenomenon “bouncing” occurs. The conclusion may help us in the optimization design of vibratory roller to some extent.