Abstract: An apparatus and a method for measuring a diode chip are provided. The diode chip is placed on a thermal conductive element. The apparatus measures an instant starting current and a first temperature, which is associated with the instant starting current, of the thermal conductive element. After the diode chip operates, the apparatus adjusts the temperature of the thermal conductive element to a second temperature, such that the current of the diode chip is adjusted to be equal to the instant starting current. The apparatus calculates a property of the diode chip according to a real power of the diode chip and a difference between the first temperature and the second temperature.