The invention discloses a method for greening a non-rock high and steep slope by using a non-woven bag. The method mainly comprises the following steps: 1, greening non-woven bag selection, namely selecting an environment-friendly non-woven bag with a degradation period of 1090-1830 days, and filling the inside of the non-woven bag with soil; 2, slope surface clearing and finishing, namely constructing a firm soil layer at the bottom of a slope surface after mechanically finishing the slope surface to remove floating stones; 3, paving a non-woven bag on the slope surface, namely transversely paving the non-woven bag on the slope surface from downside to topside, and compactly linking the non-woven bag with the whole slope surface; and 4, planting vegetations, namely uniformly forming a certain amount of holes in the surface layer of the non-woven bag, and planting vegetation seeds into the holes; and 5, conserving the vegetations. The method for greening the non-rock high and steep slope by using the non-woven bag is simple, easy to implement and capable of rapidly restoring vegetations, greatly reducing the slope greening cost and increasing the efficiency of an ecological landscape.