A new resistant germplasm, Y238, to rice bacterial blight (BB) was identified from 269 Oryza rufipogon accessions. It harbors a new BB resistance gene, WBB2, based on the resistance spectrum analysis, and comparison with all the known BB resistance genes. According to resistance reaction and genetic analysis at adult stage of progeny from JG30/Y238, the gene WBB2 is a complete dominant BB resistance gene. The new gene has been transferred into cultivated rice variety JG30 by cross and backcross for breeding a near isogenic line.