NOVELTY - The system has a sulfate reducing bacteria pre-processing unit, a hydrolysis acidification unit and a contact oxidation unit that are connected with each other. The sulfate reducing bacteria pre-processing unit is provided with a sulfate-reducing bacteria type pretreatment tank that is provided with a low intensity treatment pond and a low-intensity ultrasonic generator for transferring and refluxing filler suspension by a stripping pump and a return pipeline. The low intensity treatment pond is connected with the stripping pump and the return pipeline.    USE - The system is useful for treating polymer flooding efflux oilfield produced water (claimed).    ADVANTAGE - The system has high capacity and adaptability, and is simple in structure and convenient to use.    DETAILED DESCRIPTION - The system has a sulfate reducing bacteria pre-processing unit, a hydrolysis acidification unit and a contact oxidation unit that are connected with each other. The sulfate reducing bacteria pre-processing unit is provided with a sulfate-reducing bacteria type pretreatment tank that is provided with a low intensity treatment pond and a low-intensity ultrasonic generator for transferring and refluxing filler suspension by a stripping pump and a return pipeline. The low intensity treatment pond is connected with the stripping pump and the return pipeline. The hydrolysis acidification processing unit is provided with a hydrolysis acidification reactor that is connected with a low-intensity ultrasound treatment tank for transferring suspended filler gas by a reflux mention pump and a return pipeline. The reactor is connected with the stripping pump and the return pipeline. The sulfate-reducing bacteria pretreatment unit contains activated sludge suspension, interior porous spherical suspended filler having radial dimension of less than 50 mm, packing dosage of 20-40 vol.%. The sulfate reducing bacteria is obtained from soil, sewage and sludge collecting from polluted polymer or oil. The ultrasonic generator processes the filler gas at frequency range of 20-40 kHz and power input of 20-40 W/L for 5-20 minutes. The processed filling material is returned to the sulfate-reducing bacteria pretreating unit. The hydrolysis acidification treatment unit processes the suspension filling material at frequency of 20-40 kHz and power input of 10-40 W/L for 5-20 minutes. The contact oxidation unit comprises semi-soft filler whose surface is adhered with aerobic activity sludge. The low intensity ultrasonic wave generator is provided with a stirrer having rotating speed of 100 revolutions per minute.