A novel wireless thermometer composed of digital thermometer chip DS18B20, single-chip microcomputer and wireless RF module is designed. Its measuring temperature ranges from -55 to 125 ℃, the measuring accuracy reaches to ±0.5 ℃, and the wireless transmission distance is from 80 to 100 m. Comparing with a cable thermometer, the wireless thermometer in the measuring range has higher precise, lower power consumption and better performance-price ratio, which suitable for temperature measuring systems in greenhouses and barns. It has good application and development prospects.