The utility model discloses a phase detecting device for a 10kv switch cabinet. The phase detecting device comprises a signal acquisition module, a signal amplification module, an analysis module, an A/D converter, a display and a buzzer, the signal acquisition module is connected with a pair of XY testing pens and a ground wire in an external manner, and the XY testing pens are respectively connected with two detected ports and transmit collected circuit signals to the signal acquisition module. The signal amplification module amplifies the circuit signals transmitted from the signal acquisition module and transmits the signals to the analysis module, the analysis module figures out a phase angle difference value by the comparison from the received circuit signals and transmits the value to the A/D converter, and the A/D converter can convert the received phase angle difference value to a digital signal and transmits the digital signal to the display and the buzzer simultaneously. The phase detecting device for the 10kv switch cabinet is advantaged by wide application and safe and simple operation, results can be obtained from the display with a voice prompt.