The collaborative authoring of multimedia documents poses some special requirements of the structure and synchronization of documents. In order to make the object oriented implement of these documents easy and multiple granularity sharing of them flexible

we propose here a synchronization model for complex distributed interactive multimedia document in collaborative authoring tools. This hierarchical mode consists of three layers: page

object group

and medium object layer. Considering the characteristics of these layer

the synchronization of them are of jump based

event based

and time based mode respectively.