Synergistic herbicidal compositions

The invention relates to a synergistic herbicidal composition, and especially to a field synergistic herbicidal composition applied to crops such as resistant rapeseed and resistant soybean. A herbicidal synergistic composition is characterized by comprising a compound A and a compound B in a weight ratio of 100:1-1:100; the compound A is at least one selected from the group consisting of haloxyfop-r-methyl and fluazifop-p-butyl; and the compound B is at least one selected from the group consisting of cyclosulfamuron, bensulfuron methyl, amidosulfuron, mesosulfuron, and nicosulfuron. Through binary compound, the composition obtained by the invention has gained synergistic effect in the prevention and killing of monocotyledonous weeds and dicotyledonous weeds in the fields of resistant rapeseed and resistant soybean.