A switch detection circuit, comprising a controller , a first DC isolation module , a second DC isolation module and a signal conditioning module ; wherein an output end of the controller is configured to be connected to a first end of an external switch via the first DC isolation module , a control end of the signal conditioning module is configured to be connected to a second end of the external switch via the second DC isolation module , and an output end of the signal conditioning module is connected to an input end of the controller ; the output end of the controller is configured to output a pulse signal, and transmit the pulse signal to the second DC isolation module via the first DC isolation module and the external switch ; characterized in that the signal conditioning module is configured to output a feedback signal to the input end of the controller according to an electrical signal output by the second DC isolation module , and the controller is also configured to count the received feedback signal to obtain a count value, and detect a working state of the external switch according to the count value; wherein the first DC isolation module is a capacitor C1, the second DC isolation module is a capacitor C2 and the switch detection circuit further comprises a resistor R1 and a resistor R3; wherein a first end of the resistor R1 is connected to the output end of the controller , and a second end of the resistor R1 is connected to the first end of the capacitor C1; a first end of the resistor R3 is connected to the second end of the capacitor C2, and a second end of the resistor R3 is configured to be grounded; wherein a voltage detection end of the controller is connected to the second end of the resistor R1; and the controller is configured to detect a sampled voltage of the second end of the resistor R1 at rising edge of the pulse signal, and determine whether the external switch has a fault according to the sampled voltage and the count value. wherein an output end of the controller is configured to be connected to a first end of an external switch via the first DC isolation module , a control end of the signal conditioning module is configured to be connected to a second end of the external switch via the second DC isolation module , and an output end of the signal conditioning module is connected to an input end of the controller ; the output end of the controller is configured to output a pulse signal, and transmit the pulse signal to the second DC isolation module via the first DC isolation module and the external switch ; characterized in that the signal conditioning module is configured to output a feedback signal to the input end of the controller according to an electrical signal output by the second DC isolation module , and the controller is also configured to count the received feedback signal to obtain a count value, and detect a working state of the external switch according to the count value; wherein the first DC isolation module is a capacitor C1, the second DC isolation module is a capacitor C2 and the switch detection circuit further comprises a resistor R1 and a resistor R3; wherein a first end of the resistor R1 is connected to the output end of the controller , and a second end of the resistor R1 is connected to the first end of the capacitor C1; a first end of the resistor R3 is connected to the second end of the capacitor C2, and a second end of the resistor R3 is configured to be grounded; wherein a voltage detection end of the controller is connected to the second end of the resistor R1; and the controller is configured to detect a sampled voltage of the second end of the resistor R1 at rising edge of the pulse signal, and determine whether the external switch has a fault according to the sampled voltage and the count value. <EOS>