In order to improve the design efficiency of modified atmosphere packaging (MAP) for fruits and vegetables, a CAD method for MAP design of fruits and vegetables was studied. The CAD system was developed via MATLAB GUI based on the establishment of mathematical model of fruits and vegetables packaging, databases of respiration rate of fruits and vegetable, and database of permeability of plastic films. The system was applied in a case study. The system had clear interfaces that were easy to operate. According to the ideal gas environment parameters of products, the software could select suitable packaging materials and calculate the area or thickness of the plastic film beneficial for gas exchange. Two databases were built in the software, including the respiration rate database containing the respiration rate models for 17 fruits and vegetables, and the film permeability database containing the permeability data for 21 polymeric films. This system could facilitate quick MAP design of common fruit and vegetable products.