The invention discloses a data packet processing method and a data packet processing device which are used for processing a data packet in a network based on a software defined network (SDN) protocol. The data packet processing method comprises the steps of: receiving the data packet which is forwarded by an SDN switch in the network; acquiring a role that corresponds with a data flow in which the data packet exists; according to the received data packet, determining the data flow characteristic of the data flow in which the data packet exists; according to a predetermined matching relationship between the data flow characteristic and overtime information, determining the overtime information of the rule, wherein the overtime information indicates reserving time of the role in the flow table of the SDN switch; and transmitting the role and overtime information of the role to the SDN switch so that the SDN switch processes the data packet according to the role. Through the method and the device, overtime information of the role can be flexibly set and the performance of the SDN network is improved.