The selection of appropriate test cases is an important issue for conformance testing of protocol implementations as well as in software engineering. This paper describes an optimization method for reducing the length of protocol conformance test sequences by"Partial T sequences overlapping method", which are obtained using UIO sequences.This method provides a logical link between T method and UIO method.It is shown that test sequences generated by this method can shorter 10%-60% than those generated by other methods employing UIO sequences in an example.