In the paper, we proposed and implemented a QoS-Aware MPEG-4 authoring tool with provision of content interaction control, which is named the Q4AT system. Q4AT provides friendly user interface in a WYSWYG manner for users to create their favorite MPEG-4 scenes. The characteristics of Q4AT are as follows. (i) The description of a scene is based on the standard BIFS language. (ii) The creation of the object description is based on the syntactic description language (SDL). (iii) All descriptions are VRML-based. A VRML-based system is compatible to different browsers and operation systems. Therefore, the author could simplify the steps of creating an MPEG-4 scene. (iv) Q4AT supports the functions of the quality of service by the proposed object priority differentiation control. Using Q4AT, authors are transparent to the MPEG-4 processing layers and are capable of concentrating on the editing function usage of the Q4AT. Q4AT makes it possible to easily create a complicated MPEG-4 scene and reduce the difficulty of MPEG-4 media creation and presentation.