The invention discloses a method for detecting whether an earphone plug is inserted in place and a terminal device thereof, and the method and device relate to the detection technique and are designed to solve the problem that the prior art can not correctly detect whether the earphone plug with a microphone is inserted in place. The method adopts the technical proposal that: the method for detecting whether the earphone plug is inserted in place comprises: detecting whether the microphone part of the earphone plug is inserted in place, and outputting the detection result whether the earphoneplug is inserted in place according to the detection result of the microphone part of the earphone plug. The method for detecting whether the earphone plug is inserted in place and the device in the embodiments of the invention can be applied to visible electronic equipment such as mobile phones and PDAs.