In order to study on the genomic function and levels of evolution, a total of thirteen S9 segments of Southem rice black-streaked dwarivirus- SRBSDV representing ecological zones in Northern and Central of Vietnam was were isolated and sequenced. Sequence analysis of thirteen S9 segments from Vietnam showed 98.5 - 99.6 percent nucleotide identity. Sequence analysis of these S9 segments and seven S9 segments from China showed that S9 segments of SRBSDV isolates are highly conserved, sharing 98-100 percent nucleotide identity. Using MEGA5.2 software to construct phylogenetic tree for assessment of genetic diversity and origin arising between Vietnam's S9 segments with each other and with China's strains showed that alternating appearance between SRBSDV strains of Vietnam and China on over the trees and the closeness of the strains of the province far apart on trees indicating that they derived from a single virus population, the spread of them across different ecological zones is due to the migration of vectors - white back plant hopper. However, most of Vietnam S9 segment tends to focus on a group on a phylogenetic tree, which reflects the rapid evolution of the strain SRBSDV in Vietnam, proceed to form a new strain in the future. Analyzing secondary structure of P9.1 with RBSDV shows highly identity, suggests that P9.1 has the same role in virion assemble.