A low-power face identification method includes emitting at least one first light signal to an object, receiving at least one second light signal reflected by the object, decoding the at least one second light signal to generate a decoded light signal, extracting two-dimensional image information from the decoded light signal, performing a two-dimensional face detection function by an artificial intelligence chip according to the two-dimensional image information and two-dimensional face training data, inhibiting a two-dimensional face recognition function when a two-dimensional face is undetected, and disabling an image converter by the artificial intelligence chip in order to inhibit a three-dimensional face recognition function when the two-dimensional face recognition function is inhibited.