An apparatus for processing signals of a high-voltage loop, comprising: a filter circuit configured to filter a signal from an element to be detected in the high-voltage loop; a differential amplification circuit configured to amplify the filtered signal; and a processor configured to process the amplified signal; wherein the filter circuit connects to the element to be detected, the differential amplification circuit connects to the filter circuit, and the processor connects to the differential amplification circuit; characterized in that: the differential amplification circuit comprises a first transistor, a second transistor, and a common-mode suppression element; a first end of the common-mode suppression element connects to an emitter of the first transistor and an emitter of the second transistor, a second end of the common-mode suppression element connects to a low-voltage power supply; the common-mode suppression element is a constant-current source circuit; the constant-current source circuit comprises a third transistor, a first resistor, a second resistor, and a third resistor; a collector of the third transistor connects to the emitter of the first transistor and the emitter of the second transistor, a base of the third transistor connects to a first end of the first resistor and a first end of the second resistor, and an emitter of the third transistor connects to a first end of the third resistor; a second end of the first resistor is grounded; a second end of the second resistor connects to the low-voltage power supply; and a second end of the third resistor connects to the low-voltage power supply. a filter circuit configured to filter a signal from an element to be detected in the high-voltage loop; a differential amplification circuit configured to amplify the filtered signal; and a processor configured to process the amplified signal; wherein the filter circuit connects to the element to be detected, the differential amplification circuit connects to the filter circuit, and the processor connects to the differential amplification circuit; characterized in that: the differential amplification circuit comprises a first transistor, a second transistor, and a common-mode suppression element; a first end of the common-mode suppression element connects to an emitter of the first transistor and an emitter of the second transistor, a second end of the common-mode suppression element connects to a low-voltage power supply; the common-mode suppression element is a constant-current source circuit; the constant-current source circuit comprises a third transistor, a first resistor, a second resistor, and a third resistor; a collector of the third transistor connects to the emitter of the first transistor and the emitter of the second transistor, a base of the third transistor connects to a first end of the first resistor and a first end of the second resistor, and an emitter of the third transistor connects to a first end of the third resistor; a second end of the first resistor is grounded; a second end of the second resistor connects to the low-voltage power supply; and a second end of the third resistor connects to the low-voltage power supply. the differential amplification circuit comprises a first transistor, a second transistor, and a common-mode suppression element; a first end of the common-mode suppression element connects to an emitter of the first transistor and an emitter of the second transistor, a second end of the common-mode suppression element connects to a low-voltage power supply; the common-mode suppression element is a constant-current source circuit; the constant-current source circuit comprises a third transistor, a first resistor, a second resistor, and a third resistor; a collector of the third transistor connects to the emitter of the first transistor and the emitter of the second transistor, a base of the third transistor connects to a first end of the first resistor and a first end of the second resistor, and an emitter of the third transistor connects to a first end of the third resistor; a second end of the first resistor is grounded; a second end of the second resistor connects to the low-voltage power supply; and a second end of the third resistor connects to the low-voltage power supply.