COOL(concurrent object-oriented language) is a kind of highly efficient concurrent programming language．In this paper，a concurrent object model(concurrent C++，CCPP)and its language are presented．In this model，all objects are concurrent，and they communicate through asynchronous message sending．Concurrent objects are svnchronized using a wait-when-necessary policy，and the synchronization constrains among concurrent threads within an object are described by path expressions．CCPP is an extension of C++，implemented by a precompiler．CCPP allows sequential/concurrent rode retuse．