As a specification of middleware, real-time CORBA (common object request broker architecture) defines uniform CORBA priority which is independent of any operating system. The CORBA priority is carried with the CORBA invocation and is used to ensure that all threads subsequently executing on behalf of the invocation run at the appropriate native priority, which is mapped from that CORBA priority. How to map many CORBA priority levels to fewer native priority levels and maintain the order of these priorities is very important. The mapping problem is common in real-time middleware. The priority mapping mechanism of real-time CORBA is introduced briefly. The two methods of how to map middleware priority to native operating system priority are presented, the two methods are static mapping method and dynamic mapping method. Static mapping method is simple to be implemented, but it can break the interoperability, portability and the strict order of middleware’s priorities. Dynamic mapping method is complex to be implemented, but it can maintain the strict order of middleware’s priorities.