The present invention provides a synergistic herbicidal composition comprising a compound A and a compound B； wherein the compound A is one selected from the group consisting of clethodim and sethoxydim； wherein the compound B is one selected from the group consisting of thifensulfuron-methyl, tribenuron-methyl, cyclosulfamuron, bensulfuron-methyl, triasulfuron, mesosulfuron-methyl, monosulfuron, amidosulfuron, metsulfuron-methyl, chlorsulfuron and nicosulfuron； and the weight ratio between the compound A and the compound B is in the range from 100:1 to 1:100. The novel composition according to the present invention obtained by binary combining achieves a synergistic effect in controlling monocotyledonous weeds, dicotyledonous weeds and Cyperaceae weeds in the fields of resistant rapes and resistant soybeans.本發明提供了一種協同除草組合物，包含化合物A和化合物B，其中化合物A選自烯草酮(Clethodim)和烯禾啶(Sethoxydim)中的一種，其中化合物B選自噻吩磺隆(Thifensulfuron-methyl)、苯磺隆(Tribenuron-methyl)、環丙嘧磺隆(Cyclosulfamuron)、苄嘧磺隆(Bensulfuron-methyl)、醚苯磺隆(triasulfuron)、甲基二磺隆(mesosulfuron-methyl)、單嘧磺隆(Monosulfuron)、醯嘧磺隆(Amidosulfuron)、甲磺隆(Metsulfuron-methyl)、氯磺隆(chlorsulfuron)和煙嘧磺隆(Nicosulfuron)中的一種，化合物A和化合B的重量配比範圍為由100：1至1：100。本發明通過進行二元複配，使得所得到的新組合物在抗性油菜、抗性大豆田間的單子葉雜草、雙子葉雜草以及莎草科雜草的防除上取得了協同效果。
