In order to discuss the exogenous genes expression and effect of Bt-BADH-GA20ox-rolB multigenes on transgenic plants, four transgenic tobacco lines and a control strain were taken as materials and the experiments included determination of endogenous hormones, salt tolerance test, Bt toxic protein measurement and growth observation. The results indicated that the rooting ability of transgenic plants was enhanced. Endogenous hormones（IAA, GA3）derived from roots, stems and leaves were significantly different from controls. At a low concentration of NaCl, there is no difference between transgenic plant and control, while at 300 mmol/L of NaCl the growth of control was restrained with and the transgenic plant was normal. The Bt toxic protein was detected at a high level in both stems and leaves of the transgenic plants. The development of prodenia was obviously inhibited by feeding the leaves of transgenic plants. The transgenic plants grew vigorously after being transplanted. The average height and basal stem of transgenic plants were 1.61 and 1.37 times higher than those of control respectively.