Abstract: ［Objective］The study was carried out to construct and characterize Salmonella choleraesuis vaccine strain expressing immunogenic genes of Mycoplasma hyopneumoniae and to test its immunogenicity in mice． ［Method］We made p36，p46，p65 and p97R1-Nrdf，the main immunogenic genes of Mycoplasma hyopneumoniae，to insert into the prokaryotic expression plasmid pYA3493. Then these recombinant plasmids and pYA3493 were electroporated into C500 asd- mutant，resulting in the recombinant Salmonella choleraesuis vaccine strains C36( pYA-36) ，C46( pYA-46) ，C65( pYA-65) ，C97R1-Nrdf( pYA-97R1-Nrdf) and CpYA( pYA3493) ． We characterized these recombinant Salmonella choleraesuis vaccine strains and tested the immunogenicity in mice by intramuscular injection or orally immunized． ［Result］ The results of the immunogenicity in mice indicated that the group orally immunized with C36，C46，C65，C97R1-Nrdf showed significantly higher Mycoplasma pneumoniae antibody than both the group orally immunized with C36，C46，C65 and the group intramuscular injected with the Mycoplasma hyopneumoniae bacterin ( M + PAC) ( P ＜ 0. 01 ) ． The group intramuscular injected with C36，C46，C65 showed higher IFN-γ production than the group injected with the Mycoplasma hyopneumoniae bacterin ( M + PAC) ( P ＜ 0. 05) ，but there was no significant difference between the group orally immunized with C36，C46，C65 and the group orally immunized with C36，C46，C65，C97R1-Nrdf ( P ＞ 0. 05) ． The highest level of IL-4 was found in the group orally immunized with C36，C46，C65; higher levels of IL-4 was observed in the group orally immunized with C36，C46，C65，C97R1-Nrdf than the group injected with the Mycoplasma hyopneumoniae bacterin ( M + PAC) ; and the lowest IL-4 level was found in the group injected with C36，C46，C65. There were no significant differences among them ( P ＞ 0. 05) ． The Mycoplasma pneumoniae antibody，IFN-γ or IL-4 production of the each group was obviously higher than the control group ( P ＜ 0. 01) ． ［Conclusion］The attenuated Salmonella choleraesuis vaccine strain expressing immunogenic genes of Mycoplasma hyopneumoniae which has immunogenicity in mice especially by intramuscular injection could probably serve as a vaccine against mycoplasmal pneumonia of swine．