Abstract: By using the method of Martini isothermal analysis, the mathematic model was built on the specified construction form and the model was divided into six parts for programming. This system can be used to calculate the related performance parameters in any work condition. The main menu and Chinese manmachine interface were developed. Therefore, the system is convenient to operate and easy to read. The comparative analysis between the predicted result and testing result was made. The result shows that they can meet the requirement for design.