The invention relates to an automatic watt hour meter. The watt hour meter is located in an elevator room; the watt hour meter comprises an electric energy measurement sub system and an elevator room people counting sub system; the electric energy measurement sub system is used for detecting and outputting the output electric energy of the power frequency alternating current electricity; the elevator room people counting sub system is used for counting people passing by the current elevator room in which the watt hour meter is located every day; and the number of the people passing by the elevator room every day is used as a data basis for elevator stop control. Through the automatic watt hour meter, the measurement precision of the watt hour meter is improved; meanwhile, the equipment and space of the watt hour meter can be fully utilized; and an elevator stop control strategy which is suitable for resident travel can be flexibly made.