The invention provides a most effective method for extinguishing a mountain forest big fire, and belongs to the technical field of forest fire extinguishing. The provided most effective method for extinguishing the mountain forest big fire solves the problem that the forest big fire is difficult to extinguish within a short time, and consequently the significant loss is caused. The two leading elements for forming the big fire are combustible matter and air; due to the fact that the combustible matter cannot be cleared within a short time, people can make a fuss about air isolation; people canmanufacture the matter similar to a 'jelly' to be big or small so as to cover the height of a fire ground, (and if the jelly really cannot be manufactured to be so big, the jelly can be overlapped toreach the height); secondly, trees in the forest are high in density and hardness, due to the fact that the jelly is soft and can be easily penetrated by the trees, so that the seamless covering effect is achieved, and the jelly can be used for effectively solving the problem; and according to the overall goal, the matter is used for quickly insolating the air in the fire area, and thus the mountain forest big fire is extinguished thoroughly.