Abstract: Two derivatives of dehydroabietylamine and dehydroabietic acid, i.e., dehydroabietic-1-methyl benzoimidazol Schiff base ( 1 ) and dehydroabietic-1-methyl benzoimidazol hydrazone ( 2 ) were synthesized and characterized by FT-IR, MS, elemental analysis and 1H NMR. Their interactions with salmon sperm DNA were investigated by fluorescence spectra, viscosity analysis and circular dichronism spectra. In fluorescence spectra, different concentrations of compounds 1 and 2 were added into DNA-EB system, and with the increase of concentration, the quenching effect of fluorescence intensity of DNA-EB system was obviously occurred. The results suggested that the compounds might be inserted into the base pairs of DNA, just like EB. According to Stern-Volmer equation analysis, the interaction of compound 1 and DNA was better than that of compound 2 . With the increase of concentration of compounds 1 and 2 , the viscosity of DNA increased gradually, and the increase amplitude of compound 1 was greater than that of compound 2 . CD spectra showed that the same concentration of different compounds could make different changes of the CD signal quantity of the DNA, and the influence of compound 1 on the conformation of DNA was greater than compound 2 . The three experimental results indicated that the two compounds bound to DNA by intercalation mode. The results of agarose gel electrophoresis suggested that compounds 1 and 2 could cleave PBR322 plasmid DNA by single strand in the presence of ascorbic acid. While in the absence of ascorbic acid, only compound 1 showed the same activity. All the data showed that Schiff base had stronger DNA binding ability.