The mixed ligand complex [Pd(biqu)(pmal)]·H₂O (where biqu is 2,2′-biquinoline, pmal is phenethylmalonate) has been synthesized and its interaction with sperm DNA was determined by fluorescent spectra、 UV-Vis spectra and CD-spectra. The binding constant (K_b) of the complex and sperm DNA is 1.26×10⁴ and its interaction with pBR322 plasmid DNA was also determined by gel electrophoresis. The results show that the complex interact with DNA mainly by intercalative mode.