The invention belongs to the field of weeding, and discloses a mixing weed killer containing bentazone, acifluorfen-sodium and fluazifop-p-butyl, and an application thereof. The mixing weed killer adopts the bentazone, the acifluorfen-sodium and the fluazifop-p-butyl as main effective components, wherein a mass ratio of the bentazone to the acifluorfen-sodium to the fluazifop-p-butyl is 0.1-80:0.1-80:0.1-80, the total mass percentage of the three materials in the mixing weed killer is 1-85%. The mixing weed killer provided by the present invention can be applicable for weeding in the soybean field after seedling, specifically provides significant effects for prevention and elimination of various grassy weeds and broadleaf weeds in the soybean field. Compared to the single weed killer, in the premise of improvement of the efficacy, the weeding composition provided by the present invention delays the resistance generating of the weeds, and has wide weeding spectrum and long effective duration, and provides safeties for the soybean and the succeeding crops.