The　Ultrasonic　guided　waves　are　widely　used　in　nondestructive　test　and　structural　health　monitoring　due　to　their　ability　to　propagate　over　long　distance　in　the　structures.　However,　the　signals　of　guided　waves　are　usually　complex　and　difficult　to　analyze　because　of　the　multi-mode　phenomenon　and　dispersion　effect.　Knowledge　and　understanding　of　the　propagation　characters　of　guided　waves　is　an　important　research　subject.　The　paper　reports　a　waveform　prediction　method　based　on　spectrum　synthesis　and　phase　velocity　disperse　curves,　which　can　predict　the　waveform　of　a　specific　mode　or　a　group　modes　after　propagating　a　certain　distance.　The　waveform　prediction　algorithm　is　checked　by　experiment　and　finite　element　simulation.　Excellent　agreement　illustrates　that　the　method　is　effective.　It　shows　the　potential　of　the　method　for　wave　propagation　analysis　and　signal　processing.