A wall continuous pouring nonmetal horizontal slip form system for a deep and narrow drainage ditch comprises a unit slip form. A unit slip form body is composed of inside plates and outside plates. The inside plates are manufactured and located through adjusting type fixed supporting rods, and bottom rolling wheel shaft sleeves and bottom rolling wheels are arranged at the bottoms of the inside plates. The tops of the inside plates and the tops of the outside plates are fixed through top opposite-pull lead screws, and the surfaces of the tops of the inside plates and the surfaces of the tops of the outside plates are closed by cover plate pressing plates. The system has the beneficial effects that a novel form board is high in bending resisting and shear resisting strength and small in flexibility deformation, and the mechanical property is great superior to that of a common wood form board; plant prefabrication machining standardization and serialization are achieved, machining losses are small, and the cyclic use frequency is large; and mounting and dismounting are convenient, the workloads of form erecting and dismounting are greatly reduced, and the form board use efficiency is improved.