In ethanol medium, one ternary complex of lanthanum was synthesized using cinnamic acid, 8-hydroxyquinoline and Lanthanum chloride heptahydrate at normal temperature. The complex was tested by EDTA titration, molar conductivity, elemental analysis, infrared spectra(IR), ultraviolet spectra(UV), DTA-TG, and 1HNMR spectra. The composition of the complex was confirmed to be LaL1(L2)2•H2O (HL1= cinnamic acid; HL2= 8-hydroxyquinoline). The antimicrobial properties of Escherichia coli, Staphylococcus aureus, Staphylococcus albus, Bacillus subtilis and Micrococcus luteus showed that: lanthanum ion, 8-hydroxyquinolin and complex had an antibacterial effect, but antibacterial effect of the complex was significantly superior to the ligands.