The most commonly used temperature measuring instrument in reality is the infrared thermometer, which is usually very accurate, but requires a high level of environmental requirements. Infrared forehead thermometer, the environment required in the outside temperature of 16-35 ℃. If it is currently winter, the outdoor cold, the card point will be very low body temperature, this situation of long-term exposure to the temperature measurement instrument will appear error, such as the measurement of the body temperature will be low, the personnel for a long time in the cold environment to measure the forehead temperature will also be a certain gap. If the measurement is not proper, such as the thermometer is too close to the skin or too far away from the body temperature deviation will also occur. If there is a temperature error, it is recommended that the thermometer be replaced with a mercury thermometer in time for another measurement.