The Audio/Video Stream Specification was brought forward by OMG (Object Management Group) based on the extension to traditional CORBA (common object request broker architecture) architecture. Multimedia applications could get more benefits, such as open and standard, from the distributed object computing brought by this Specification. However, there is not a whole scheme in the specification to solve the security problem of distributed multimedia applications. Because of this immature security, a security stream model―SecStream is presented, which brings the CORBA security service and the data security service into the old stream architecture. Subsequently, design and implementation of the above model are discussed. Finally, the SecStream model is successfully applied to an application, where the flexibility and extensibility of this model are verified.