In order to verify that a high-power marine gas turbine engine can be redesigned to be a reversible one, concept verification was done on a reversible turbine test rig. The reversible power turbine test pieces were designed, which are transformed to be capable of rotating reversely. And more than 100 times of operational tests were done for the switching devices. Based on the reversible turbine test rig, 50 times of switching tests between normal and reverse rotational direction were done by compressed air under low temperature condition. While more than 100 times of operational tests were done with hot gas at temperature of 400–500 °C. The tests results show that the switching devices could operate flexibly and the output power reached over 40% of rated power condition. During the switching tests between the normal and reverse rotational direction, the propeller could stop running. All of these verify the concept feasibility of reversible gas turbine engine. Based on this concept, preliminary design was completed for a high-power marine gas turbine engine redesigned into a reverse one, which laid solid foundation for the following detailed design, experimental verification and application.