The work aims to explore a new type environment friendly composite scale and corrosion inhibitor for oilfield produced water treatment. By taking advantage of static scale inhibition test, static weight-loss method, polarization curve and electrochemical impedance spectroscopy, the scale and corrosion inhibition on N80 carbon steel was investigated in simulated quality of oilfield produced water. The propotion of polyepoxysuccinic acid, ATMP and hydrolytic polymaleic anhydride were determined by virtue of orthogonal experiment. In addition, the optimum formula of the scale and corrosion inhibitor was determined and its added amount in oilfield produced water was tested to be 20 mg/L. The scale and corrosion inhibitor could be used in treating oilfield produced water of high content of calcium and pH value within 6.0～8.0. Its scale inhibiting ratio could be up to more than 90%. The polarization curve and electrochemical impedance spectroscopy showed that the scale and corrosion inhibitor was a mixed-type inhibitor mainly restraining the cathodic process of metal. The corrosion-inhibiting rate could be up to more than 82% when 20 mg/L of the inhibitor was added to the oilfield produced water, reducing the corrosion rate significantly and meeting requirements of industry standards. The scale and corrosion inhibitor was prepared easily and provided with excellent scale and corrosion inhibition performance.