The utility model discloses a lower simply instrument of weeding of membrane, its include handle, connecting rod, setting at the hoeing knife of connecting rod front end piece subassembly, hoeing knife piece subassembly include crescent hoeing knife, T shape buckle spare, thread connection post, with the butterfly nut of thread connection post looks adaptation, crescent hoeing knife's border department all sets up the cutting edge, is provided with the arc track that slides at crescent hoeing knife middle part, T shape buckle spare can follow crescent hoeing knife bottom pass the arc slide the track with be located the slide thread connection support connnection on track upper portion of arc, thread connection post one end is connected with the connecting rod, the other end is connected with T shape buckle spare, can be with crescent hoeing knife centre gripping between T shape buckle spare and butterfly nut when butterfly nut and the cooperation of thread connection post, the utility model has the advantages of reasonable design, the user demand is satisfied to the position of the relative connecting rod of adjustable crescent hoeing knife, can clear away, do benefit to to the inside weeds of plastic film and loosen the soil difficult the wound to the plastic film.