A new Bismuth(Ⅲ)-Lanthanum(Ⅲ) heterobimetallic polymer complex,{[(H2O)5La(μ4-edta)Bi(NO3)2]·3H2O}n(edta=diaminetetraacecarboxylate),has been hydrothermally synthesized and characterized by elemental analysis,FT-IR,and X-ray diffraction single crystal structure analysis.It crystallizes in the monoclinic system,with space group P2(1)/n,a=1.27395(5)nm,b=0.82608(4) nm,c=2.38819(11) nm,β=104.9000(10)°,V=2.42879(19) nm3,Z=4,Dc=2.438 g·cm-3,μ=9.077mm-1,F(000)=1678,R1=0.0343,wR2=0.0906.In this complex,Bi atom is coordinated by four carboxyl O atoms from a single edta4-anion.La atom is bonded to four O atoms from four bridging carboxyl O atoms belonging to four different edta4-anions and five O atoms from five H2O molecules.Bi atoms and La atoms are linked by bridged edta4-anions,resulting into a novel infinite 3D network structure.TG-DSC and IR indicate that thermal decomposition proceeds in several stages,dehydration,pyrolysis of ligand,and finally decomposition of salt,and the residue is composite oxide based on δ-Bi2O3 at the temperature of 600℃.