A probe for an ear thermometer has a mounting bracket, a light module, a temperature sensor and a probe tube. The light module and temperature sensor is mounted on the mounting bracket. The light module is capable of radiating different colored lights to respectively indicate normal or abnormal body temperature. The probe tube covers the light module and temperature sensor and is light-pervious. Because the probe of the ear thermometer indicates the body temperature by different colored lights and/or numerals, using the ear thermometer with the probe is easy, simple and instinctive when compared to conventional thermometers that use LCD display to show numerical values.