The invention relates to improvement of a green belt for roads and is characterized in that the surface of the green belt is lower than a road surface. The quickly seeping green belt is composed of a greening vegetation layer, a permeable soil layer and a grit layer which are sequentially arranged from top to bottom, and a permeable drain pipe is arranged in the grit layer. Accordingly, the green belt has the greening function and filtering and quick draining functions simultaneously and solves the problem of water gathering on the road surface when it rains. Besides, rain water which is drained and seeps to the underground is purified water filtered by vegetation, soil and grit. In addition, the green belt further expands rain water absorbing area and can collect more rain water to supplement underground water. Therefore, the green belt for roads effectively overcomes the insurmountable shortcomings of a design method of an existing green belt higher than the ground, and has a novel function which a green belt in the prior art cannot have.