A dry-type transformer temperature monitoring system has been designed with STC89C51 at the coreand new digital temperature sensor DS18B20 as the field detection device. Wireless Communications between control unit and master computer has been completed and the monitoring interface of master computer has been designed used VC programming language. The system can detect and display multiplex temperature signal and alarm when the temperature is higher than stated value. The practical application in the dry-type transformers with the type of SCZ10-10000/35 proved that the reliability and anti-interference of this systemcan meet the experimental demands.