Abstract: The fundamental principle of flow-jet boiling enhancing is proposed. The water column caused by normal pressure water thrusts through the water layer at a certain velocity to directly contact the plate surface. A nuclear boiling area can be established and intensive boiling will occur. The effect of the extreme cooling area on the entire cross section of the steel plate can be obtained via an optimized experimental research on the outlet velocity, height, diameter of flow jet and distance between adjacent water columns. For a plate of 20 mm thick, the cooling speed is up to 45.2℃/s and the shape precision up to 3 mm/m.