Test ModelThis paper adopts TTCN-3 as test implementation technology, which is widely used in protocol testing. Reference [7] presents a test configuration scheme of TTCN-3.In TTCN-3, the components which are in charge of executing test case can be divided into MTC (Main Test Component) and PTC (Parallel Test Component). First, the test system creates MTC to start test execution. Then MTC can create several PTCs to invoke the IUT (Implementation under Test) to execute test case. MTC can also coordinate the execution of PTC according to test flow, and implement intercommunication via message queue mechanism. As TTCN¬3 is an abstract testing language, the interaction between TTCN-3 test system and object under test uses abstract test system interface, and real test system interface is replaced by adapter in test execution.Referring to the descriptions in Fig. 1 and Fig. 2, this paper establishes the model of interoperability testing between operating systems, as shown in Fig. 3. Test system is composed of one MTC and two PTCs, MTC is responsible for creating PTCs and coordinating the test process among PTCs. Two PTCs are connected to two operating systems under test separately via respective adapter, whose purpose is to deliver test command and return execution results.