The invention provides a regression method and a regression device of a mower. The method comprises the following steps: recording the mowing cumulative time of the mower in the work period of a battery in real time; if the cumulative time reaches to a preset first threshold value, seeking a regression guide signal, wherein the regression guide signal is used for guiding the mower to return to a charging station to charge; and when finding the regression guide signal, returning to the charging station to charge according to the regression guide signal. By the method, the capacity of the mowerbattery does not need to be increased, so that waste of energy is avoided; and when the mowing cumulative time of the mower in the work period of the battery reaches to the preset first threshold value, the mower automatically seed the regression guide signal, so that the condition that the mower does not return to the charging station to charge before the electric quantity of the mower is exhausted can be avoided.