Abstract: Based on the discussion of shortcomings of the close CAI, this paper proposes away to create an object-oriented open hypermedia CAI system, and describes the general thoughts, main functional modules and keytechniques of buildingthis open hypermedia CAI systemusingthe object-oriented programdesigning language C++. The design of changeable-assembling media data and the method of linking CAI systems and model-building systems with Windows API interface are expounded in the paper; they have some generality and good practicability.