In view of the difficulty of treating oily sewage in heavy oil polymer injection oilfield，phenolamine resin was synthesized using bisphenol-A，formaldehyde and triethylenetetramine as the main raw materials，and then a series of bisphenol-A phenolamine polyether clearing agents with multi-branched chain，multi-amine group and multi-phenylene ring were synthesized from phenolamine resin as the starting agent. The effect of the clearing agent was analyzed by studying the changes of oil-water interface properties before and after the addition of clearing agent. The clear water effect of the synthetic series of clear water agent was evaluated by reducing the oil content of wastewater to less than 20 mg/L within 3 min after adding clear water agent，from which clear water agent F-14 and F-15 were selected，and the clear water effect of the compounded clear water agent was investigated in different compounding ratios，and field application experiments were conducted. The results showed that the clear water agent F-14 and F-15 are compounded according to the compounding ratio of 2∶1，and the oil content of the sewage could be reduced to 18 mg/L at the dosing rate of 40 mg/L within 3 min，which met the standard requirements. the synthetic clear water agent had strong interfacial activity，which could easily adsorb at the oil-water interface and repel the original surface-active material at the oil-water interface to form a new oil-water interface film. The newly formed interface film was weak and easy to rupture， resulting in colliding between small oil droplets and gathering easy to form large oil droplets，promoting the separation of oil and water，so as to achieve the clear water effect of oily sewage. The results of the field trial in an oilfield in Bohai Sea showed that the synthetic clear water agent was suitable for short flow and polymer containing sewage quality，and the oil content in the treated injection water was below 20 mg/L，meeting the field technical requirements.