The aim of this study was to construct a Deltaasd mutant of Salmonella choleraesuis as an asd+ balanced-lethal host vector for carrying heterogeneous antigens. The authors had constructed successfully the Deltacrp mutant of S.choleraesuis Smith, herein the authors continued with Deltaasd mutant gene of this strain. The Deltaasd was created from upstream (2112bp) and downstream (2069bp) fragments of asd, and cloned respectively into the cloning vector to get pBSIIK+/Deltaasd with the l480bp deletion mutant. Deltaasd was then separated from the cloning vector by XbaI/KpnI, inserted into suicide plasmid pRE112, and transformed into S. cholearasuis 539/Deltacrp for the allelic exchange. The DeltaasdDeltacrp S. choleraesuis got the DL-alpha.e-DiaminoDimelic acid dependent growth. Other biochemical characteristics including growth kinetic, colony size, sugar fermentation, were changed compare with the parent strain (S. choleraesuis Smith). Sequencing result of the tlasd gene show that the deleted fragment was located from 434th to 1909th nucleotide in the 2340bp asd gene. The asd mutant gene was stable in the DeltaasdDeltacrp S.choleraesuis genome.