The invention provides a control method and
system of the switch-off process of a
relay of a
power battery. The control method comprises the following steps: after receiving a command of switching off the
relay, judging whether the conditions of switching off an
anode relay are satisfied or not according to the running states of a vehicle and a
power battery system, and if yes, sending out a command of switching off the
anode relay so as to switch off the
anode relay; and after switching off the anode relay, judging whether conditions of switching off a
cathode relay are satisfied or not according to the running states of the vehicle and the
power battery system, and if yes, sending out a command of switching off the
cathode relay so as to switch off the anode relay. Therefore, according to the control method disclosed by the invention, the running states of the vehicle and the power
battery system are comprehensively considered, and the corresponding relay can be switched off only when the switch-off conditions are satisfied, wherein the switch-off conditions include the failure level, the interval time of states, and the constraint conditions of
electric current and conform to the actual running states of the vehicle and the power
battery system. Thus, the service life of the power
battery system is prolonged, and the safe running of the vehicle is guaranteed.