The invention provides a pinoxaden and bromoxynil octanoate compound emulsifiable concentrate and a preparation method thereof, and relates to the technical field of prevention and control of annual broad-leaf weeds in wheat fields. According to the present invention, 100 parts of the pinoxaden and bromoxynil octanoate compound emulsifiable concentrate is prepared at least from 5 parts of pinoxaden, 25 parts of bromoxynil octanoate, 7.5 parts of tristyrylphenol polyoxyethylene ether, 7.5 parts of distyrylphenol formaldehyde condensation compound polyoxyethylene ether, 15 parts of calcium dodecylbenzenesulfonate, and the balance of xylene; pinoxaden and bromoxynil octanoate are added to xylene, stirring is performed until both materials are dissolved, the remaining raw materials are added, uniform stirring and mixing are performed through a reaction kettle, sampling is performed and the content is analyzed, standing is performed after the qualified standard is achieved, filtration and packaging are performed, sampling is performed again and the content is analyzed, and warehousing is performed after the qualified standard is achieved; and the obvious synergistic effect can be provided when the 30% pinoxaden and bromoxynil octanoate compound emulsifiable concentrate is subjected to mixing use according to the ratio of 1:5 while the obvious synergistic effect cannot be achieved with the other preparations being subjected to the mixing use according to a certain ratio.