To clone and analyze variable region gene sequences of mouse monoclonal antibody against human S100A9( anti-human S100A9 mAb). Total RNA was extracted from the hybridoma cell line( Ⅱ D4B10)secreting mouse anti-human S100A9 mAb. Furthermore,the heavy chain variable region( VH) and light chain variable region( VL) genes were amplified using reverse transcription-polymerase chain reaction( RT-PCR). After the cloning and sequencing of the VHand VLgenes,the sequence analyses were performed by BLAST program. The VLgene,a member of the mouse IGKV14-111* 01 family,had an open reading frame( ORF) of 291 bp with 97 amino acids,and the VHgene,a member of the mouse IGHV1-80* 01 family,had an ORF of 324 bp with 108 amino acids. In addition,the sequences of VH and VLgenes presented the characteristics of antibody variable region with individual frameworks and complementarity determining regions. The variable region gene sequences of mouse anti-human S100A9 mAb have been successfully obtained,which are helpful to construct genetically engineered antibody in the future.