Wheat spot blotch disease, caused by Bipolaris sorokiniana, is a devastating disease that can cause severe yield losses worldwide. Although inoculum levels can be reduced by planting disease-free seed, treatment of plants with fungicidesand crop rotation, genetic resistance is likely to be a robust, economical and environmentally friendly tool in the controlof spot blotch. We found a spot blotch disease resistance gene Sb3 on chromosome 3BS in Chinese wheat line 621-7-1(Lu et al. 2016). The Sb3 was fine mapped in a 0.096 centimorgan (cM) genetic interval spanning a 380 kb physical genomicregion. RNA-seq analyses of ethylmethane sulfonate (EMS) mutagenized B. sorokiniana susceptible M3 families revealedG/A sitemutations, resulted in amino acid codon changes, were only occurred in a transporter (TP) gene in the candidate mapping interval in 8 independent mutants. Preliminary functional validation was performed by transforming an overexpressed TP gene into susceptible line 621-18-3. Two of the positive T0 transgenic plants were conformed to be resistant to spot blotch. This is the first report of map based cloning of a spot blotch resistance gene and will shed light on the understanding of molecular interaction between wheat and B. sorokiniana.