The present invention relates to a sodium salt of a uric acid transporter inhibitor and the crystalline form thereof. In particular, the present invention relates to the sodium salt of a uric acid transporter (URAT1) inhibitor, and the I-type crystal and the preparation method thereof. The present invention relates to 1-((6-bromo-quinoline-4-yl)thio)cyclobutyl sodium formate (the compound of formula (I)), and the I-type crystal and the preparation method thereof. The I-type crystal of the compound of formula (I) obtained in the present invention has a good crystal form stability and chemical stability, and the crystallization solvent used has a low toxicity and low residue, and can be better used in clinical treatment.