A fault identification apparatus, comprising: a detector; a plug interface connected with the detector and comprising a first measuring terminal and a second measuring terminal; a resistor; and a direct current power source connected with the detector and the plug interface wherein, when the fault identification apparatus is connected to a power supply unit PSU in a communication apparatus under test, the first measuring terminal is configured for connecting with a first end of the PSU and the second measuring terminal is configured for connecting with a second end of the PSU; a negative pole of the direct current power source is connected with the second measuring terminal; and the detector configured for obtaining a voltage value between the first measuring terminal and the second measuring terminal to determine whether a failure occurs to the PSU based on the voltage value; wherein when determining whether the failure occurs to the PSU based on the voltage value, the detector is configured for: when the voltage value is greater than or equal to a first threshold and less than or equal to a second threshold, determining no failure occurs to the PSU, wherein the second threshold is greater than the first threshold, when the voltage value is less than the first threshold, determining the failure occurs to the PSU; and when the voltage value is greater than the second threshold, determining the failure occurs to the PSU, the fault identification apparatus being characterized in that: a positive pole of the direct current power source is connected with a first end of the resistor, a second end of the resistor is connected with the first measuring terminal, the first threshold is greater than a sum of forward voltages of two diodes, and the second threshold is less than a voltage value of the direct current power source. a detector; a plug interface connected with the detector and comprising a first measuring terminal and a second measuring terminal; a resistor; and a direct current power source connected with the detector and the plug interface wherein, when the fault identification apparatus is connected to a power supply unit PSU in a communication apparatus under test, the first measuring terminal is configured for connecting with a first end of the PSU and the second measuring terminal is configured for connecting with a second end of the PSU; a negative pole of the direct current power source is connected with the second measuring terminal; and the detector configured for obtaining a voltage value between the first measuring terminal and the second measuring terminal to determine whether a failure occurs to the PSU based on the voltage value; wherein when determining whether the failure occurs to the PSU based on the voltage value, the detector is configured for: when the voltage value is greater than or equal to a first threshold and less than or equal to a second threshold, determining no failure occurs to the PSU, wherein the second threshold is greater than the first threshold, when the voltage value is less than the first threshold, determining the failure occurs to the PSU; and when the voltage value is greater than the second threshold, determining the failure occurs to the PSU, the fault identification apparatus being characterized in that: a positive pole of the direct current power source is connected with a first end of the resistor, a second end of the resistor is connected with the first measuring terminal, the first threshold is greater than a sum of forward voltages of two diodes, and the second threshold is less than a voltage value of the direct current power source. when the voltage value is greater than or equal to a first threshold and less than or equal to a second threshold, determining no failure occurs to the PSU, wherein the second threshold is greater than the first threshold, when the voltage value is less than the first threshold, determining the failure occurs to the PSU; and when the voltage value is greater than the second threshold, determining the failure occurs to the PSU, the fault identification apparatus being characterized in that: a positive pole of the direct current power source is connected with a first end of the resistor, a second end of the resistor is connected with the first measuring terminal, the first threshold is greater than a sum of forward voltages of two diodes, and the second threshold is less than a voltage value of the direct current power source. a positive pole of the direct current power source is connected with a first end of the resistor, a second end of the resistor is connected with the first measuring terminal, the first threshold is greater than a sum of forward voltages of two diodes, and the second threshold is less than a voltage value of the direct current power source.