The invention discloses a two-stage thermoelectric power generation device for ship waste heat recovery and a power generation method. The device comprises a fume pipeline, a hexahedral structure, a thermoelectric power generation mechanism and a cooling plate structure; a section of pipeline is cut from the middle of a ship incinerator exhaust pipe and replaced with the fume pipeline; the front end of the fume pipeline is a fume inlet, the rear end of the fume pipeline is a fume outlet, and the outside of the fume pipeline is wrapped with the hexahedral structure; the thermoelectric power generation mechanism comprises two-stage thermoelectric power generation units; the cooling plate structure comprises two-stage cooling plates; the first-stage thermoelectric power generation unit is tightly close to the outer wall of the hexahedral structure, and the first-stage cooling plate, the second-stage thermoelectric power generation unit and the second-stage cooling plate are arranged on the outside of the first-stage thermoelectric power generation unit sequentially. According to the two-stage thermoelectric power generation device for ship waste heat recovery and the power generationmethod, a way of efficiently recycling ship incinerator high-temperature exhaust gas waste heat in stages and using the waste gas for power generation is provided, the high-temperature exhaust gas waste heat can be directly converted into electric energy, energy gradient utilization is realized, the utilization amount of the waste heat is increased, and the device power is improved.