Disclosed are a p-toluenesulfonate for an MEK kinase inhibitor, and a crystal form thereof and a preparation method therefor. Specifically, disclosed are a 2-((2-fluorine-4-iodophenyl)amino)-1-methyl-4-((6-methylpyridine-3-group)oxygroup)-6-carbonyl-1,6-dihydropyridine-3-formamide p-toluenesulfonate (a compound represented by formula (I)), and an I-form crystal and a preparation method therefor. The obtained I-form crystal of the compound represented by formula (I) has good crystal form stability and chemical stability, and a used crystallization solvent has low toxicity and low residue and can be better used in clinical treatment.
