The invention discloses a high-sensitivity spiral capacity coupling sensor and an installing method thereof. The high-sensitivity spiral capacity coupling sensor comprises metal copper sheet electrodes, an insulating spacer, a ground electrode and a sensor body. The installation method comprises the steps of adhering the metal copper sheet electrodes to the insulating spacer to form the capacity coupling sensor; winding the capacity coupling sensor around an outer shielding layer of a cable in the clockwise direction, wherein it is ensured that the insulating spacer is well bonded with the outer shielding layer; leading the metal copper sheet electrodes out through a sensor outgoing line after spiral winding is conducted by three circles, wherein the metal copper sheet electrodes are 44 mm wide, and the distance between the metal copper sheet electrodes is 45 mm. According to the high-sensitivity spiral capacity coupling sensor, spectral response peak value reaches 1400 mV, center frequency is 17 MHz, and bandwidth is 10 MHz; spectral response amplitude value and bandwidth can be increased effectively, sensitivity of partial discharge detection of the capacity coupling sensor can be improved, and the defects of existing capacity coupling sensors that spectral response amplitude value and bandwidth are small are overcome.