Abstract: Triglycol ester acid maleate as an intermediate product was prepared by using five-ring maleic anhydride and triethylene glycol as raw materials and then reacted with calcium/zinc acetate to obtain a functional monomer with multifunctional groups. There are ester groups, carbonyl groups, ether bond and conjugated double bond in the molecules of maleic acid monotriethylene glycol ester. Afterward, a heat stabilizer was obtained by mixing maleic acid monotriethylene glycol ester with calcium/zinc salt. The content of metal ions was determined by titration with a standard solution of edetate disodium, and the chemical structure of the heat stabilizer was characterized by FTIR spectroscopy, and its thermal stabilizing effect on PVC was investigated by means of a thermal oven aging method, Congo red test, conductivity test and thermogravimetric analysis. Moreover, the synergetic stabilizing effect of this thermal stabilizer with β-diketone (Stearoyl benzoylmethane) was also evaluated. The results indicated that there was a good synergistic effect on enhancement of thermal stability when the mass ratio of calcium/zinc triglycol ester acid maleate was set to 1.5/1. The initial whiteness of the specimen could maintain 50 min, and the static thermal stability time reached 29 min, indicating that the heat stabilizer developed by this work has a better stabilizing effect than the normal calcium/zinc stearate one. An optimum stabilizing effect was achieved when 10 wt% of β-diketone added was added into this heat stabilizer.