An operating method of a mobile device includes determining a plurality of moving directions of a mobile device corresponding to a plurality of time points according to an acceleration sensing signal; determining a plurality of distances between the mobile device and an external wireless signal transmitter corresponding to the time points according to a wireless signal from the external wireless signal transmitter; calculating an average moving speed of the mobile device according to the moving directions and the distances between the mobile device and the external wireless signal transmitter; estimating an estimating moving direction of the mobile device according to the moving directions; and selectively outputting an operating requirement according to the average moving speed and the estimating moving direction of the mobile device, to make an external device operates an instruction corresponding to the operating requirement.