Abstract: Cationic polymer CY-16 was synthesized to solve the problem of low-temperature oily wastewater. A series of evaluation tests with fresh wastewater demonstrated that, compared to other wastewater treatment chemicals often used in oilfields, CY-16 can achieve high efficiency both on oil removal and on suspended solids (SS) at extensively low cost. Under the condition of 15 mg·L^-1 CY-16 + 5 mg·L^-1 HPAM, water temperature 25℃, and sedimentation time 30 min, the final mass concentration of oil in treated wastewater decreased to no more than 10 mg·L^-1, that of SS no more than 30 mg·L^-1, and the median particle size of SS about 3.0μm.