In recent years, varying traffic patterns and evolving applications are urging the Internet revolution. Traditional networking components are hard to achieve perfect condition facing the traffic demands from applications. Hence, Open Flow, a software defined network solution is proposed to gain flexible configuration and dynamic control on networking devices. It provides an opportunity to design mechanisms toward better transmission guarantee. The Open Flow protocol provides multiple actions in packet forwarding process. However, there are few accordant designs in hardware support differentiating or shaping the traffic up to this point. On the other hand, most of the developing methods with complicated control policies in software defined network such as traffic shaping and prioritized packet processing are concentrating only on software-based level. Therefore, this paper proposes a prioritized packet-processing module with offloaded flow control mechanism on to an embedded platform, NetFPGA, with open and programmable networking interface. The implementation enables incoming packets on each port of an Open Flow-enabled switch to be processed according to different priorities. Also, the designed control mechanism focuses on minimizing resource competition among flows, and its policies can be modified by software to dynamically limit the output rate on egress ports. Experiment results show that the prioritized packet-processing module with output rate control mechanism reaches a decent accuracy in both TCP and UDP connections, which provides desired traffic shaping and flow priority functions. This work also provides a prototype solution for differentiating traffic by service demand on networking device in software defined network environment.