The invention provides a protection method for an inclined slope on a river bank of a quasi ecological lake. Ditches are dug on the sloping surface of the inclined slope on the river bank and made to be lengthways and widthways connected to form a network shape, each ditch has a width of 30 cm to 40 cm and a depth of 25 cm to 30 cm. For an inclined slope on a river bank made of sandy soil, the area in a shell frame formed among the ditches is from 3m<2> to 4m<2>. For an inclined slope on a river bank made of viscous soil, the area in a shell frame formed among the ditches is from 5m<2> to 6m<2>. A mode of permanent planting with high density is adopted, hygrophytes are planted in the ditches, cover plants are planted in the shell frame formed among the ditches, and emergent aquatic plantsand submerged plants are planted at the lower part of the sloping surface. The invention has simple construction and low cost, can have the action for preventing flushing and protecting an earth mound, is propitious to conserve water and soil and lower the sloping surface flushing degree, provides the living environment for animals, plants and microorganisms, enables the ecological system on the sloping bank to keep stable, and has the action for beautifying the environment.