We always use timeline to describe time, but timeline unable to describe dynamic time. Because dynamic time is on changing, so timeline must be changing too, but it is impossible. Timeline includes layers, relationships existed between layers. If we changed a layer, the others need to be fixed too. Timeline can not make it up automatically, human being must take the work, therefore real-time-changing becomes impossible. It is no matter for film making, but internet needs instant responding, timeline can not cover it. Here we show a new structure called timetree, it is an auto-balanced hierarch structure. Its structure always be complete during changing without help from human being. It is a challenge for making dynamic interactive contents on internet, timetree is borned for it. We have tried timeline before, now it is the turn of timetree.