The invention provides a water-cooled precombustion device which is characterized in that the water-cooled precombustion device comprises a precombustion chamber component and a flame nozzle; the precombustion chamber component is fixedly arranged in an inner cavity, and comprises a precombustion chamber housing vertically embedded into the inner cavity, and a spark plug arranged in the precombustion chamber housing; the precombustion chamber housing comprises a precombustion chamber upper seat and a precombustion chamber cavity housing that are arranged from the top down sequentially; the flame nozzle is detachably arranged on the precombustion chamber cavity housing, and comprises a cylindrical barrel provided with a cavity; a plurality of penetrating flame channels and a plurality of nozzle cooling water channels are formed in the cylindrical barrel; the nozzle cooling water channels and the flame channels are arranged in a staggered manner; a through hole between the precombustion chamber component and an air cylinder cover acts as a water inlet channel; and cooling water is introduced into the water inlet channel via an exterior internal combustion engine circulation line, and then enters the nozzle cooling water channels, and the cooling water flows in the nozzle cooling water channels, undergoes heat exchange and then flows out. The water-cooled precombustion device can allow the flame nozzle to be cooled and be subjected to heat dissipation, the heat dissipation efficiency is high, and the service life of the flame nozzle of a precombustion chamber can be prolonged.