A fingerprint sensor, comprising: a fingerprint sensor chip; and a floating ground control circuit; the fingerprint sensor chip comprising: a sensor array having a plurality of sensing electrodes, the sensing electrodes in the sensor array configured to form a fingerprint capacitor with a finger; a driver configured to output a driving signal to the floating ground control circuit; a sensor power supply end connected to the floating ground control circuit and configured to receive a high potential output from the floating ground control circuit; and a sensor ground connected to the floating ground control circuit and configured to receive a low potential output from the floating ground control circuit; the floating ground control circuit comprising: a booster circuit connected to a power supply, configured to boost a voltage output by the power supply and generate a high voltage signal to be provided to the sensor ground; a switch circuit comprising a first switch arranged between the power supply and the sensor power supply end, a second switch arranged between the booster circuit and the sensor ground, and a third switch arranged between a device ground and the sensor ground, wherein: a first control signal, a second control signal, and a third control signal are generated from the driving signal via conversion, and configured to respectively control the first switch, the second switch, and the third switch; the first switch and the third switch are configured to switch ON and OFF states synchronously, and the ON and OFF states of the second switch and the ON and OFF states of the first switch and the third switch are opposite, such that the low potential supplied to the sensor ground and the high potential supplied to the sensor power supply end synchronously and periodically vary relative to the device ground, to thereby maintain a constant voltage which is supplied to the fingerprint sensor chip. a fingerprint sensor chip; and a floating ground control circuit; the fingerprint sensor chip comprising: a sensor array having a plurality of sensing electrodes, the sensing electrodes in the sensor array configured to form a fingerprint capacitor with a finger; a driver configured to output a driving signal to the floating ground control circuit; a sensor power supply end connected to the floating ground control circuit and configured to receive a high potential output from the floating ground control circuit; and a sensor ground connected to the floating ground control circuit and configured to receive a low potential output from the floating ground control circuit; the floating ground control circuit comprising: a booster circuit connected to a power supply, configured to boost a voltage output by the power supply and generate a high voltage signal to be provided to the sensor ground; a switch circuit comprising a first switch arranged between the power supply and the sensor power supply end, a second switch arranged between the booster circuit and the sensor ground, and a third switch arranged between a device ground and the sensor ground, wherein: a first control signal, a second control signal, and a third control signal are generated from the driving signal via conversion, and configured to respectively control the first switch, the second switch, and the third switch; the first switch and the third switch are configured to switch ON and OFF states synchronously, and the ON and OFF states of the second switch and the ON and OFF states of the first switch and the third switch are opposite, such that the low potential supplied to the sensor ground and the high potential supplied to the sensor power supply end synchronously and periodically vary relative to the device ground, to thereby maintain a constant voltage which is supplied to the fingerprint sensor chip. a first control signal, a second control signal, and a third control signal are generated from the driving signal via conversion, and configured to respectively control the first switch, the second switch, and the third switch; the first switch and the third switch are configured to switch ON and OFF states synchronously, and the ON and OFF states of the second switch and the ON and OFF states of the first switch and the third switch are opposite, such that the low potential supplied to the sensor ground and the high potential supplied to the sensor power supply end synchronously and periodically vary relative to the device ground, to thereby maintain a constant voltage which is supplied to the fingerprint sensor chip.