In this research, ZnAlLa‐itaconate‐LDHs was synthesized by means of Co‐precipitation‐hydrothermal method. The effects of aluminum‐lanthanum ratio, co‐precipitation time, hydrothermal time, and hydrothermal temperature on the crystal structure were studied. As a result, the optimum condition was found to be: n(Al3+): n(La3+) = 10:1, co‐precipitation time 24 h, hydrothermal time 8 h, and hydrothermal temperature 180°C. The influence of ZnAlLa‐itaconate‐LDHs on the thermal stability properties and plasticizing properties of PVC were investigated, exhibiting long‐term stability of 76 min with short plasticizing time of 1.11 min. Long‐term thermal stability mechanism was studied by FTIR before and after hydrochloric acid treatment. It was demonstrated that the thermal stabilizer ZnAlLa‐itaconate‐LDHs prevented the rupture of the CCl bond in PVC and inhibited the development of HCl. Consequently, impeded the production of CC bond and playing a role in thermal stabilization of PVC.