Three new rare earth ternary complexes (NdLL'•4H2O, EuLL'•4H2O and LaLL'•4H2O) have been prepared with rare earth nitrates, tryptophan (L) and sodium citrate (NaL'). The characteristics of the complexes were identified by elemental analysis, IR, molar conductivity solubility and TG-DTA. The results showed the complexes have constant composition of RELL'•4H2O. And all of the rare earth ternary complexes have anticoagulant action.