With the deepening of oil well drilling，conventional drag reduction can no longer meet the performance and environmental protection requirements of cementing cement under new working conditions. An environmental polycarboxylate oil well cement drag reducer （HZ-1） was synthesized through free radical polymerization reaction using polycarboxylate superplasticizer polyether（TPEG-2400），sodium methacrylate sulfonate（SMAS），acrylic acid and other raw materials. The optimum synthesis conditions were optimized through orthogonal experiments. The structure and thermal stability of HZ-1 were analyzed by infrared spectroscopy， nuclear magnetic resonance hydrogen spectroscopy， thermogravimetric analysis and synchronous thermal analyzer. Indoor evaluation of the drag reduction，temperature resistance and environmental protection of HZ-1 was conducted according to the standards of oil and gas industry. The drag reduction mechanism of HZ-1 was explored through the changes in adsorption capacity，steric hindrance and Zeta potential. The results showed that the optimum preparation conditions for HZ-1 were obtained as follows：10 g SMAS，0.41 g sodium hypophosphite，175 g TPEG-2400，7.6 g hydrogen peroxide，0.91 g ascorbic acid，22.22 g acrylic acid，20 g 20% sodium hydroxide，dropwise addition time of 2.0 h，reaction temperature of 20 ℃，and reaction time of 0.5 h. HZ-1 had good thermal stability and a decomposition temperature of 338 ℃. The cement slurry system prepared by mixing 0.40% HZ-1 with oil well cement at a water cement ratio of 0.44 had good drag reduction performance，the flowability index of 1.033，the consistency coefficient of 0.023 Pa · sⁿ，the compressive strength of 18.413 MPa，and the temperature-resistance capacity up to 170 ℃. HZ-1 had good biodegradability and environmental protection. Its EC₅₀（half effective concentration）was 36 307 mg/L，COD（chemical oxygen demand）was 571 984 mg/L，and BOD₅（biochemical oxygen demand）was 196 330 mg/L. The ratio of BOD₅/COD was 0.3432. So the biological grade of HZ-1 was non-toxic. The greater the steric hindrance of HZ-1，the better the rheological property of cement slurry was. The adsorption curve of HZ-1 on the surface of cement particles met the Langmuir adsorption model，which was the chemisorption of single molecular layer. HZ-1 reduced the Zeta potential on the surface of cement particles and enhanced its electrostatic repulsion，thus enhancing the rheological properties of cement slurry.