The work aims to solve the problem of corrosion in oilfield produced water. A composite corrosion inhibitor for oilfield produced water treatment was prepared, and the influence of environmental factors on corrosion inhibition was studied to provide theoretical basis for scientific anticorrosion of oilfield produced water. A green composite corrosion inhibitor was made from phosphonic imidazoline quaternary ammonium salts and sodium tungstate. Corrosion inhibition of the composite corrosion inhibitor was evaluated in dynamic weight-loss method, and effects of medium temperature, PH value, salinity and flow rate on corrosion resistance were systematically studied. The corrosion inhibition rate of Q235 steel was 0.0269 mm/a when optimum mass concentration of the composite corrosion inhibitor was 60 mg/L provided with water temperature of 55 ℃, pH=7, flow rate of 2.5 m/s and salinity of 36 g/L, it could meet the standard requirements of oilfield produced water reinjection. The corrosion rate in oilfield produced water decreased as mass concentration of the inhibitor increased, and increased as the temperature rose. The corrosion rate was greatly affected at the salinity of 32 g/L, and slightly affected at the flow rate of 1.2~3.0 m/s or pH value of near neutral level. The composite corrosion inhibitor is a environmental friendly inhibitor for oilfield produced water treatment and is of high inhibition efficiency.