A method for testing multi-protocol implementation under test (IUT) with a single test suite has been proposed in the literature. It tests a multi-protocol IUT in an integrated way compared to the conventional method, where single-layer test method and single-layer embedded test method are applied separately to the upper layer protocol and lower layer protocol, respectively. However, it did not consider how to generate the test cases automatically but proposed only an approach for the test method. This thesis proposes an algorithm called Multi-protocol Test Method (MPTM) for automatic test case generation based on that approach. With the MPTM, a multi-protocol IUT consisting of two protocol layers is modeled as two Finite State Machines (FSMs), and the relationships between the transitions of them are defined as a set of transition relationships, pre-execution and carried-by. The proposed algorithm is implemented and applied to a simplified TCP/IP and B-ISDN Signaling/SSCOP. The MPTM is able to test the multi-protocol IUT even though the interfaces between the protocol layers are not exposed. It also allows the same test coverage as conventional test methods with much smaller number of test cases and operations.