Abstract: The presentation layer protocol is a part of OSI upper layer protocols.The current research, the process, and the basic methods of protocol conformance testing are introduced. The requirement of conformance testing for the presentation layer protocol is analyzed.Using the ANS.1 and TTCN formal description language,the conformance testing system and test suite for the kernel of the presentation layer protocol are designed and implemented. The conformance testing for the presentation layer protocol implementation within ISODE is also passed. Conformance testing system for the presentation layer protocol is one of subsystems of PCTS （Protocol Conformance Testing System）. This subsystem has been successfully implemented, that will be useful for exploring other upper layer protocols of the computer network.