Abstract: On the basis of the analysis of the thermodynamic properties of refrigeration, the buildup of mathematical models and the application of Object-Oriented windows Programming (OOP), a CAI software for the rotary compressor has been developed successfully. The software has three main functions:cartoon demonstration, thermodynamic calculation and design calculation. Thermodynamic properties of common refrigerants can also be read up from the software conveniently. It is a modernized CAI incorperating integrity, practicality and vividness, which has been used in the classroom instruction and course design and achieved satisfying result