The invention provides a herbicide prepared by binary combination of oxyfluorfen and 
pendimethalin and 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 
pendimethalin, 5 to 15 percent of synergist, 8 to 20 percent of emulsifier and the balance of 
solvent. The preparation method comprises the following steps of: mixing the oxyfluorfen and the 
solvent in the 
mass ratio and stirring the mixture; mixing the 
pendimethalin and the 
solvent and stirring the mixture; mixing the obtained solution; adding the emulsifier, the synergist and the obtained mixture in a reaction kettle, and stirring the mixture in the reaction kettle for 10 to 15 minutes; adding the remained solvent into the mixture, and stirring the mixture for 20 to 30 minutes; and performing standing, filtering, filling and sampling analysis to obtain the finished product. The herbicide is a high-efficiency 
contact type broad-spectrum herbicide; when the herbicide is used for controlling annual gramineae and 
cyperaceae monocotylous and dicotyledons 
weed,, such as soy beans, wheat, potatoes, cotton, tobacco, vegetables and melon-fruit plants, in tea gardens and orchards, the effect is produced in 2 to 3 hours, and the 
weed is died in 3 to 5 days, and after one time of 
pesticide application, the harmful 
weed can be removed in the whole growing periods of plants. The dosage of the herbicide is 25 to 35 grams per mu, and the application cost of the herbicide is 57 to 43 percent lower than the sole application cost of the oxyfluorfen or the pendimethalin.