According　to　the　experience　of　vibratory　compaction,　a　nonlinear　soil　dynamic　model　was　built.　This　model　represents　the　dynamic　characteristic　of　different　soil　compacted　process　including　elastic-plastic　nonlinearity　and　jump　vibration.　Based　on　the　first　order　approximation,　the　equivalent　damping　coefficient　and　equivalent　stiffness　coefficient　was　deduced　through　the　harmonic　linearization　method.　By　means　of　numerical　simulation,　the　dynamic　characteristic　of　roller-soil　system　was　studied.　During　the　beginning　of　vibratory　compaction,　soil　represents　elastic-plastic　characteristic　and　the　roller　keeps　coupling　with　soil.　During　the　ending　of　vibratory　compaction,　density　of　soil　increases　and　sub-harmonics　may　occur.　When　roller　takes　a　jump　vibration,　chaos　motion　could　be　induced.　Adjustment　of　excitation　amplitude　and　excitation　frequency　could　availably　restrain　the　jump　vibration　and　chaos　motion　of　roller.