San Fior is a comune (municipality) in the Province of Treviso in the Italian region Veneto, located about north of Venice and about northeast of Treviso. As of 31 December 2004, it had a population of 6,357 and an area of .
San Fior borders the following municipalities: Codogné, Colle Umberto, Conegliano, Godega di Sant'Urbano, San Vendemiano.
San Fior is divided into three villages: the principal town is San Fior (or San Fior di Sopra); the south frazione is San Fior di Sotto and the north frazione is Castello Roganzuolo.
San Fior is twinned with: