Electronic thermometer is expected to be a best seller because it meets the market's need better, easier to use and less mercury pollution. Electronic thermometer based on Bluetooth Low Energy (BLE) is able to work for months only with a coin-cell battery. In this paper, the proposed monitoring system, comprised of a temperature acquisition module, a BLE module and smart phones, is able to acquire temperature data through the sensor, display on LCD screen, transmit the temperature result via the BLE wireless link and display the temperature on smart phones too. Smart phones can write values to control the thermometer as well. Results show that implementation of BLE technology in this system has the lower power consumption.