Conformance testing of TCP/IP protocol is the first step for interoperability among Internet network products.The conformance testing of the Internet protocol with a PITS (protocol integrated test system) is presented in this paper.The authors use the distributed test method and remote traverse test method to test IP (Internet protocol) end system and IP relay system in Internet,respectively.IP test suite in TTCN (tree and table combined notation) is derived according to IP test purposes.Furthermore,the IP conformance testing has been applied for developing routers.