The present invention relates to a latch mechanism and a tenon structure thereof. The tenon structure includes a trigger portion and a fastening rail portion adapted to be respectively installed at a hollow opening and a side edge of a sliding cover plate to accordingly achieve a single-piece tenon structure. The tenon structure is connected to the sliding cover plate, moves in a second direction along with the sliding cover plate, and is capable of displacing in a first direction relative to the sliding cover plate. The tenon structure includes a front latch portion and a trigger portion exposed at the sliding cover plate, so as to achieve effects of a simple assembly structure and reduced production costs.