Herbicide used in rape field, prepn. method and use thereof

The present invention relates to a canola herbicide, method of preparation and use thereof. The rapeseed herbicide comprising as an active ingredient at least a compound of structural formula. The herbicide emulsifiers, solubilizers, stabilizers and solvents further mixed to prepare a emulsifiable concentrate, can be safely used rape fields before or after emergence of weeds can be used, it is common not only controlling gramineous weeds, and Control can be part of broad-leaved weeds, but also controlling Poa vicious weeds. With high efficiency, low toxicity and environmental friendliness.