The paper presents a method which supports the test of a new network protocol. We design a normal and agility interface for the testers to define and construct the packets of a new protocol, then transform the packets to a  standard protocol type while the system working under the existing condition. The testers do not concern the switching process, and it is transparent. The testers initialize the structure of the packets,construct packets, set up the interface parameters and run the testing process to get the results. Experimentations indicate that the system is more compatibile, flexible and friendly.