The invention provides an earphone in-place detection circuit and a detection method. The circuit comprises a main processor, an audio processor, an earphone in-place detection circuit, a microphone signal line, a left channel signal line, a right channel signal line and a key signal line, the earphone in-place detection circuit comprises a comparator, a first resistor, a second resistor, a thirdresistor and a fourth resistor, a microphone signal line is connected with one end of a magnetic bead, and a key signal line is connected with a GPIO port of the main processor; the left channel signal line is connected with a left channel port of the audio processor, and the right channel signal line is connected with a right channel port of the audio processor. A microphone signal line, a key signal line, a first sound channel signal line and a second sound channel signal line are respectively connected with a first capacitor, a second capacitor, a third capacitor and a fourth capacitor which are grounded, so that high-frequency interference introduced from the outside is suppressed; and grounded transient voltage suppression diodes are respectively connected to prevent static electricity from damaging the signal interface.