Abstract: In the medium of anhydrous ethanol,the complexes of REL₂L'·nH₂O(RE:Nd³⁺,Eu³⁺,La³⁺, Sc³⁺; L:all-trans retinoic acid; L':L-valine acid) were synthesized at 60℃. The compositions of these complexes were tested by means of infrared spectra(IR),ultraviolet spectra(UV),elemental analysis and TG-DTA methods. Meanwhile,the antitumor activity against HepG2,A549 and Hela in vitro growth cells was investigated by MTT test method. The results show that these four synthesized rare earth complexes inhibit the growth of HepG2,A549 and Hela cells in different degrees. The inhibition rates of these complexes are significantly higher than that of rare earth nitrate and ligands. The interaction of REL₂L' complex with DNA was studied by fluorescence spectroscopy and viscosity measurement. The results show that the type of interaction is mainly intercalation, which results in the antitumor activity of these complexes. This investigation provides certain ideas and experimental basis for the design of efficient rare earth antitumor drugs with low toxicity.