Insect pests attacks caused large rice yeild and economic loss every year. Brown planthopper (BPH, Nilaparvata lugens) is one of the most grievous insects of rice. The most effective measure to avoid its large-scale damage is developing BPH resistance lines and cultivating resistant varieties. Guangxi Indica rice germplasm 47-1 is highly resistance at seedling and adult stage for three consecutive years which proved that 47-1 had good genetic stablity, and shows 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 resistance mechanism. In this study, we developed one F2 population containing 91 individuals by crossing 47-1 and a susceptible line 9311. After that, the BPH resistance level of each plant was identified by insect weight gain. The results showed that 61 resistant individuals having BPH weight increased multiple < 1.1 and 30 susceptible individuals with multiple > 1.1 were obtained. Chi-square test (χ2=3.081<χ20.01,1=3.84) showed that the ratio was consistent with the separation rule of one pair of dominant genes. One BPH resistance locus was detected in the region harbored by markers 04M0.453 and 04M3.688 on chromosome 4, which was considered to be the allele of Bph40. Only 3bp substitutions in the CDS of the Os04g08390 amplified from variety 47-1 were different from that of Bph40, which caused two amino acid differences in the protein. Phylogenetic tree analysis showed that Os04g08390 of 47-1 was closely related to Bph40. Overall, we proposed that it is a Bph40 allele that contributes to the resistance of 47-1.