The temperature resistance of the current polymer drilling fluid treatment agents is poor and cannot meet the requirements of deep and ultra-deep high temperature drilling. In addition，the sulfonated materials is limited because of environment protection. Using N，N-dimethylamine，oxalic acid，and CA catalyst as the main raw materials，the temperature-resistant synergist HAS was prepared by optimizing the monomer ratio，reaction temperature and time. The temperature resistance and synergistic performance of HAS in more than 10 kinds of polymer solutions such as the coating agent polyacrylamide potassium salt KPAM，high temperature resistant polymer viscosity increasing fluid loss agent driscal-D，temperature resistant salt resistant viscosity increasing agent BDV-200S，and in low viscosity carboxymethyl cellulose sodium salt LV-CMC bentonite drilling fluid，polymer potassium chloride drilling fluid，was evaluated. Furtherly，the biological toxicity of HAS was detected by the bioluminescence bacteria method. The results showed that when the molar ratio of N，N-dimethylamine to oxalic acid to CA catalyst was 1∶3∶2，the reaction temperature was 70℃ and the reaction time was 8 hours，the yield of HAS prepared was the highest，reaching up to 98%. The temperature-resistant synergist HAS had an obvious temperature-resistant synergistic effect on most polymer solutions，which could increase the temperature resistance of BDV-200S polymer from 180℃ to more than 220℃ ，and the temperature resistance of LV-CMC bentonite drilling fluid from 80℃ to 150℃，the temperature resistance of the polymer potassium chloride drilling fluid system reached up to 150℃. After adding HAS，the drilling fluid had stable rheological properties and high viscosity retention， which was equivalent to that before aging. The API fluid loss was reduced by more than 50%，and inhibition performance was improved greatly. The EC50 of HAS，measured by the bioluminescent bacteria method，was 2.76 × 105 mg/L，indicated that HAS had no biological toxicity.