Two mutants of the zinc finger protein, ZNF191(243-368) I323W and R327W, are successfully obtained by site-directed mutagenesis. The fluorescence spectrum is used to study the interaction between these two mutants and the oligonucleotides. The influence of the mutation on the interaction has been studied using ethidium bromide (EB) as the fluorescence probe. The binding constants of theI323W-DNA and R327W-DNA have been calculated and the possible binding models have been discussed.