This paper deals with the data model for multimesha objects. which is one of the crucial problems ofmultimexha database systems First. the characteristics of multimesha data are discussed. the existing multimedia data models are mmlyzed and the schema architecture of a multimesha database system Is presented. which is based on cncept and presentation modeling Secondly, a fonnal concept model for inulttmedia objects is defined Finally. the problem of spatio-temporal composition of multimedia objects is discussed. and a presentation model for multimedia objects is denfined.