A small form factor transceiver module includes a base, a printed circuit board, a cover, a heatsink and an adhesive. The printed circuit board has a connecting terminal. The printed circuit board is sandwiched between the base and the cover. The cover has at least one first groove and a mounting surface away from the printed circuit board. The first groove is located on the mounting surface. The adhesive is connected between the mounting surface and the heatsink. The first groove is configured to accommodate an excessive portion of the adhesive.