Brown planthopper （BPH， Nilaparvata lugens） is one of the most disaster insects of rice. The most effective measure to prevent its damage is developing BPH resistance lines and cultivating resistant varieties. The indica rice germplasm 47-1 from Guangxi， China， is highly resistant at seedling and adult stage for three consecutive years， thus proving the genetic stability and the significant antibiosis and antixenosis against BPH. In order to enrich the gene diversity of BPH resistance and breed resistant rice varieties， it is meaningful to map its resistance gene and explore its mechanism. In this study， we developed by crossing 47-1 and a susceptible line 9311 a F₂ population containing 91 individuals， followed by identifying the insect weight gain. 61 and 30 individuals， each of which showed the BPH weight increased ≤1.1 and >1.1， respectively， were obtained （Chi-square test： χ²=3.081<χ²_0.01，1=3.84）， suggesting that this locus is genetically controlled by one pair of single dominant gene. This locus was delimited to the region flanked by markers 04M0.453 and 04M3.688 on chromosome 4， where the BPH resistance gene Bph40 is present. Three substitutions in the coding sequence of Bph40（t） differing with that of Bph40 were detected in variety 47-1， which resulted in two amino acid substitutions in the protein. Phylogenetic tree analysis showed that the Bph40（t） haplotype from 47-1 was closely related to the Bph40. Collectively， these results implied that the BPH resistance gene in 47-1 is a novel allele of Bph40.