The invention discloses a herbicide prepared by binary compounding of oxyfluorfen and trifluralin and a preparation method thereof. The herbicide consists of the following components in percentage by mass: 3 to 10 percent of oxyfluorfen, 10 to 30 percent of trifluralin, 5 to 15 percent of surfactant, 8 to 20 percent of emulsifying agent and the balance of solvent. The preparation method comprisesthe following steps of: in the mass ratio, adding solvent into the oxyfluorfen, and mixing and stirring; adding solvent into the trifluralin, and mixing and stirring; mixing and stirring the two mixtures; adding the emulsifying agent and the surfactant into a reaction kettle, stirring 10 to 15 minutes; adding the rest solvent, and stirring for 20 to 30 minutes; and standing, filtering, filling, and sampling and analyzing to obtain the finished product. The herbicide is a high-efficiency and broad-spectrum herbicide, and is used for tending tea gardens, orchards and young growth and preventingand removing weeds before and after seedlings come out after seeds of crops such as soybean, rape, potato, cotton, cabbage, hot pepper, sunflower and tobacco are sowed. 30 to 40 g of herbicide is used for each mu at one time, and can realize no weeds in the whole growth period of the crops; and the application cost is 56.4 to 44.3 percent lower than that of the oxyfluorfen and the trifluralin.