This paper aims at studying the microcomputer control for the refri-gerating installation of middle or small size. The schematic diagram of software de-sign, the principle of connection line for input and output interface, the microcomputercontrol system for the installation and the designs of software and hardware for auto-defrost system of energy-save type were studied in the paper. The microcomputer controlhas the features of small dimension, high controllability, good stability and reliability,low cost, etc, and is appropriate to the self-test and real-time control of the refrigeratinginstallation in the process of running. Hence, it will help commercialize the energysave defrosting system for the refrigerating installation by microcomputer control.