The disclosure provides a method device and system for recording an attendance. The method includes that: a Femto (74) receives a registration request or a de-registration request of a mobile terminal (72), wherein the registration request or the de-registration request includes an identifier of the mobile terminal (72); and the Femto (74) saves the identifier of the mobile terminal (72) and time corresponding to the registration request or the de-registration request of the mobile terminal (72) together to serve as an attendance record of a user corresponding to the mobile terminal (72). The method, device and system for recording an attendance solve the problems of great configuration difficulty and high cost of a system for implementing attendance recording in related technologies, and realize fully-automatic attendance statistics; and this implementation mode is easy to operate and low in cost.