The invention relates to the electric automobile technology and discloses a double-battery-system discharge control method. The method specifically includes the following steps that during power-on, electric quantities in two battery systems are monitored and compared, and then a battery with the higher electric quantity is selected to serve as a currently-used battery. The invention further discloses a double-battery-system discharge control system. The system specifically comprises a battery electric quantity monitoring unit, a comparison unit and a selection unit. The battery electric quantity monitoring unit is used for monitoring the electric quantities in the two battery systems. The comparison unit is used for comparing the electric quantities in the two battery systems and sending the comparison result to the selection unit. The selection unit is used for selecting the battery with the higher electric quantity to serve as the currently-used battery during power-on. Control over double-battery discharge is achieved through the method.