A position detecting system and method for an electronic device used an audio signal input module of the electronic device and a signal receiver to connect to the audio signal input module convert an external position signal into an audio signal. A position detecting software running on the electronic device analyzes the audio signal. Accordingly, the current position of the electronic device is obtained. The audio signal input module of the electronic device is employed as an input port for the external position signal, thus saving the construction cost of the system. Besides, the current position of the electronic device with an ever-changing position can be obtained during a test process, such that the electronic device can start or stop a test item accordingly.