The invention discloses a tenon tooth clamping and positioning device for an aircraft engine power turbine working blade. The device comprises a base, the base is used for supporting and fixing a bottom, a positioning seat for clamping a blade tenon tooth is fixedly connected on the base, the positioning seat comprises a fixed socket portion and a movable clamping head, the blade tenon tooth is inserted and clamped from a side tenon groove through the fixed socket portion, the movable clamping head slides after the blade tenon tooth is clamped to form tenon tooth groove staggered teeth, so that a blade to be detected is fixed and positioned through the movable clamping head, a sliding channel is formed in the middle of the fixed socket portion, connected with the movable clamping head in an inserted manner and slides in the fixed socket portion, the fixed socket portion is provided with a first tenon tooth groove and a second tenon tooth groove which penetrate the sliding channel, theblade tenon tooth is inserted and clamped through the first tenon tooth groove and the second tenon tooth groove, the movable clamping head is provided with a third tenon tooth groove, the blade tenontooth is inserted and clamped through the third tenon tooth groove, the first tenon tooth groove, the second tenon tooth groove and the third tenon tooth groove form a penetrated continuous tenon tooth groove and are matched with the shape of the blade tenon tooth, one group of parallel clamping force is formed, and accuracy of subsequent detected data is ensured.