in recent years many researchers have been focused on interaction of small molecules with dna. dna is generally the primary intracellular of anticancer drugs, so the interaction between small molecules and dna can cause dna damage in cancer cells, blocking the division of cancer cells and resulting in cell death. the flavonoids are a large group of polyphenolic natural products that are widely distributed in higher plants. quercetin (q:3, 3, 4, 5, 7-pentahydroxyflavone) is a strong hydroxyl-antioxidant and a major dietary flavonoid most common present in nature. it is generally found in many common foods including apple, tea, onion, nuts cauliflower and cabbage. the biological activities of q are influenced by the presence of metal ions. hydroxy and oxo groups present in q structure have the ability to form complexes with various metal cations to form stable compounds. in this work, complex of a with bi(iii) and sn(ii) ion have been synthesized and characterized using spectroscopic methods. then, the antioxidant activities of the compound was evaluated using 1,1-diphenyl-2-picrylhydrazyl (dpph) radical scavenging method, ferric reducing activity (frap) and abts assay. also the interaction of q-bi(iii) complex and q-sn(ii) complex with ct-dna has been investigated using uv-vis spectra, impedance spectroscopy , fluorescence, and spectroscopy. the three dpph, frap and abts assays show that the antioxidant power of complex is low than q. since the antioxidant activity of flavonoid depends on the number and positions of oh groups in the flavonoid structure, the results express oh position in q structure replaced by bi(iii) ion and therefore the ability of hydrogen donating of complexes is low as compared to the free q. the data of impedance spectroscopy is show the interaction between of complexes and dna.the hyperchromicity of the absorption spectra q–sn(ii) complex were observed in the presence of dna and the binding constantans (kb) was 5× 105. the fluorescence intensity of q–sn(ii) complex was decresed with the addition of dna and binding constantans dna to complex was obtained 8×105 that is the the range of uv data. the relative viscosity of dna increased with the addition of q–sn(ii) complex. hyperchromism of the absorption spectra q-bi (iii) complex were observed in the presence of dna, and the fluorescence intensity of q-bi (iii) complex was enhanced with the addition of dna. the relative viscosity of dna increased with the addition of q-bi (iii) complex. the binding constant of q-bi(iii) was obtained 105. the data has shown that the binding of both complexes to dna, through non-intercalative mode and out-side binding mechanism and interaction of both complexes with dna through phosphate group is present in the dna structure.