The reactions in mixtures of water-ethanol between lanthanide salts and nitrogen N-hetrocyclic carboxylic acid,in the presence of ammonium oxalate,result in the interesting lanthanide-organic coordination polymers,formulated as,{[Sm4(Hmimda)4( 4-C2O4)2·6H2O]·8H2O}n,(H3mimda=1H-2-methyl-4,5-imidazole-dicarboxylic acid).The title polymers are built from zig-zag 1-D chains constructed from Ln-Hmimda moieties bridged by oxalate,as the secondary building unit(SBU).The Hmimda ligand further is interconnected the 1-D chains to form the 3-D framework.Variable-temperature magnetic susceptibility measurements indicate that the μ4-k4 O bridging fashion of oxalate results in the possible antiferromagnetic interactions occurring between the adjacent lanthanide(Ⅲ)centers.The photo-luminescent and thermalgravimetric analyses of the polymers were also determined.