A method for processing a Graceful Restart, GR, of an OpenFlow switch in an OpenFlow network which adopts an architecture where a control plane and a forwarding plane are separated, wherein the control plane is implemented by a device having a powerful computing capability, the device being referred to as an OpenFlow controller, and the forwarding plane is implemented by a device having a switching capability, the device being referred to as an OpenFlow switch, and the OpenFlow switch is connected with the OpenFlow controller; the method comprising: determining, by the OpenFlow controller, the OpenFlow switch being in a GR state; marking, by the OpenFlow controller, a state of the OpenFlow switch as the GR state, wherein marking the state as the GR state comprises: keeping still valid a flow table of the OpenFlow switch and the external connection between the OpenFlow controller and the OpenFlow switch, as before the GR, and prohibiting the flow table from being modified; and detecting, by the OpenFlow controller, a re-connection with the OpenFlow switch; and clearing, by the OpenFlow controller, the GR state of the OpenFlow switch; wherein determining, by the OpenFlow controller, the OpenFlow switch being in the GR state comprises: receiving, by the OpenFlow controller, a GR notification message sent by the OpenFlow switch after detecting a GR trigger event; and determining, by the OpenFlow controller, the OpenFlow switch being in the GR state according to the received GR notification message; or, sending, by the OpenFlow controller when connecting with the OpenFlow switch, to the OpenFlow switch a message for inquiring whether the OpenFlow switch supports a capability of the GR; receiving, by the OpenFlow controller, a GR supporting capability response message fed back by the OpenFlow switch; and determining, by the OpenFlow controller when disconnecting from the OpenFlow switch, the OpenFlow switch being in the GR state according to the received GR supporting capability response message. determining, by the OpenFlow controller, the OpenFlow switch being in a GR state; marking, by the OpenFlow controller, a state of the OpenFlow switch as the GR state, wherein marking the state as the GR state comprises: keeping still valid a flow table of the OpenFlow switch and the external connection between the OpenFlow controller and the OpenFlow switch, as before the GR, and prohibiting the flow table from being modified; and detecting, by the OpenFlow controller, a re-connection with the OpenFlow switch; and clearing, by the OpenFlow controller, the GR state of the OpenFlow switch; wherein determining, by the OpenFlow controller, the OpenFlow switch being in the GR state comprises: receiving, by the OpenFlow controller, a GR notification message sent by the OpenFlow switch after detecting a GR trigger event; and determining, by the OpenFlow controller, the OpenFlow switch being in the GR state according to the received GR notification message; or, sending, by the OpenFlow controller when connecting with the OpenFlow switch, to the OpenFlow switch a message for inquiring whether the OpenFlow switch supports a capability of the GR; receiving, by the OpenFlow controller, a GR supporting capability response message fed back by the OpenFlow switch; and determining, by the OpenFlow controller when disconnecting from the OpenFlow switch, the OpenFlow switch being in the GR state according to the received GR supporting capability response message. receiving, by the OpenFlow controller, a GR notification message sent by the OpenFlow switch after detecting a GR trigger event; and determining, by the OpenFlow controller, the OpenFlow switch being in the GR state according to the received GR notification message; or, sending, by the OpenFlow controller when connecting with the OpenFlow switch, to the OpenFlow switch a message for inquiring whether the OpenFlow switch supports a capability of the GR; receiving, by the OpenFlow controller, a GR supporting capability response message fed back by the OpenFlow switch; and determining, by the OpenFlow controller when disconnecting from the OpenFlow switch, the OpenFlow switch being in the GR state according to the received GR supporting capability response message.