1. A method for recording an attendance, comprising: receiving, by a Femto, a registration request or a de-registration request of a mobile terminal, wherein the registration request or the de-registration request comprises an identifier of the mobile terminal; and saving, by the Femto, the identifier of the mobile terminal and time corresponding to the registration request or the de-registration request of the mobile terminal together to serve as an attendance record of a user corresponding to the mobile terminal; wherein after saving, by the Femto, the identifier and the time corresponding to the registration request or the de-registration request of the mobile terminal together, the method further comprises: obtaining, by an attendance platform, the identifier of the mobile terminal and the time corresponding to the registration request or the de-registration request of the mobile terminal which are saved in one or more Femto; and collecting statistics, by the attendance platform, to attendance records of the user corresponding to the mobile terminal according to the identifier of the mobile terminal and the time corresponding to the registration request or the de-registration request of the mobile terminal; wherein collecting statistics, by the attendance platform, to the attendance records of the user corresponding to the mobile terminal according to the identifier of the mobile terminal and the time corresponding to the registration request or the de-registration request of the mobile terminal comprises: the attendance platform reading, in a database, a correspondence table for the identifier of the mobile terminal and a name of a user whose attendance is to be recorded; according to the correspondence table for the identifier of the mobile terminal and the name of the user whose attendance is to be recorded, the attendance platform replacing, in a correspondence table for the identifier of the mobile terminal and the time corresponding to the registration request or the de-registration request of the mobile terminal, the identifier of the mobile terminal with the name of the user corresponding to the mobile terminal to generate an attendance record table of the user.