The invention discloses a lesson sign-in system based on face recognition. A control unit matches received student face image information with face image information of class attending students stored in an information storage unit; if matching is successful, a control unit obtains the practical position of a target student through a positioning unit, and if the practical position of the target student is within a preset range, the control unit judges that the target student carries out successful signing; if the practical position of the target student exceeds the preset range, the control unit judges that signing of the target student fails; if matching fails, the control unit judges that signing of the target student fails, and the control unit transmits the student face image information transmitted through an information collecting unit to the information collecting unit for storage and transmits the signing failure information of the target student to the information collecting unit.