Titanium dioxide-polyaniline/polyamide 6 (TiO₂-PANI/PA6) composite nanofibers were prepared by in situ polymerization of aniline in the presence of PA6 nanofibers and a sputtering-deposition process with a high purity titanium sputtering target. TiO₂-PANI/PA6 composite nanofibers and PANI/PA6 composite nanofibers were fabricated for ammonia gas sensing. The ammonia sensing behaviors of the sensors were examined at room temperature. All the results indicated that the ammonia sensing property of TiO₂-PANI/PA6 composite nanofibers was superior to that of PANI/PA6 composite nanofibers. TiO₂-PANI/PA6 composite nanofibers had good selectivity to ammonia. It was also found that the content of TiO₂ had a great influence on both the morphology and the sensing property of TiO₂-PANI/PA6 composite nanofibers.