Usually the thermometer is more accurate belongs to the mercury thermometer, because the location of the mercury thermometer measurement is the deep human body temperature, such as intraoral body temperature, axillary body temperature and anal body temperature, are measured through the mercury thermometer. And the opposite of mercury thermometer is electronic thermometer, also called electronic thermometer gun, there are currently infrared temperature measurement thermometer, the above thermometer compared to mercury thermometer is more prone to error, electronic thermometer is measuring forehead and measuring the temperature behind the ear. But will be subject to the environment, the surrounding temperature and the level of regulation of human neurons and certain effects, such as the outside environment temperature is relatively high, in the summer measurement will appear when the body temperature is high, in the winter measurement will appear when the body temperature is relatively low.