Abstract: Due to the limitation of thermal degradation of PVC, thermal stabilizer must be added when processing, it makes thermal stabilizer becoming a rapidly growing field. However, The rare earth stabilizer have a unique electronic structure, so they can form complexes with such many organic compounds including the coordinated atoms: N and O which used as PVC thermal stabilizer. Amide type open chain of rare earth ions have a strong ability of coordination and high selectivity, we can obtain with new structure complexes at the same time, which has received the widespread attention. In this paper, maleic anhydride, ethylene diamine, sodium hydroxide, lanthanum chloride, zinc chloride and calcium chloride as the raw material, adopts the direct legal system had not reported three kinds of complexes, the N-amino ethyl maleamic acid lanthanum(LaL3), ZnL2,CaL2.And through their recombination to study the synergistic effect between them and the impact on the thermal stability of PVC. By melting point determination, element analysis, infrared spectrum, such as the composition, structure and properties were studied. Congo red test and TG analysis shows that the three kinds of complexes have good thermal stability of PVC. By these three composite heat stabilizers, suggests LaL3/ZnL2 and CaL2/ZnL2 composite heat stabilizer on PVC thermal stability increased significantly, and could effectively suspend “zinc burning”. Key words：complexes of lanthanum(Ⅲ) ; N-(2-amino ethyl) maleamic acid radical (L-) Lanthanum (III) ; Polyvinyl chloride (PVC)；Heat stabilizer