The present invention relates to the technical field of pesticides, particularly relates to a pyrazole compound or a salt thereof, a preparation method therefor, a herbicidal composition and use thereof. A pyrazole compound of formula (I) or a salt thereof: wherein, R1 represents hydrogen or C1-C4 alkyl; R2 represents C1-C3 alkyl; R3 represents C1-C6 linear chain or cyclic group containing one or more heteroatoms selected from O, S, and N; R4 represents C1-C3 alkyl or halogen; R5 represents pyrazole ring or pyrazole ring substituted with one or more groups selected from alkyl, alkoxyl, halogen, halogenated alkyl, amino, and nitro. The pyrazole compound is an excellent herbicide with broad spectrum biological activity and outstanding safety for crops.