Disclosed are a pyrazole compound or a salt thereof, and a preparation method, a herbicide composition and a use thereof. The pyrazole compound or salt thereof has the structure as shown in formula (I). In the formula (I), R represents , wherein R', R'' and R''' represent hydrogen atoms, C1-C4 alkyl, C1-C4 halogenated alkyl, C1-C4 alkyloxy or halogen, and may be the same or different； R1 represents a C1-C3 alkyl； R2 represents a hydrogen atom or C1-C4 alkyl； and R3 is a hydrogen atom or C1-C6 alkyl, a substitutable phenyl, a substitutable pyridyl, a substitutable alkenyl, a substitutable alkynyl, a C1-C6 alkylcarbonyl, a C1-C6 alkyloxycarbonyl, a C1-C6 alkylcarbonylmethyl and the like. The pyrazole structure not only shows an excellent herbicidal effect on barnyard grass, but is also safe to apply to rice after seedling emergence. More surprisingly, it also exerts an outstanding effect on barnyard grass with resistance to the main barnyard grass herbicides such as penoxsulam, quinclorac, cyhalofop-butyl and propanil.
