In the field of papermaking, the water jet cutting is an indispensable equipment. Its principle of action is to spray a very thin water column (diameter ≤ 2mm) onto the surface of the blanket, and cut the cloth pulp on the blanket so as to guide the paper. A smooth and convenient water needle is the key to the success or failure of paper threading, especially on high-speed paper machines such as household paper machines, where the basic weight of the produced paper is low (generally not more than 40g/m2), and the key to the success of paper pickup factors.