NOVELTY - Bio-agent combined treating method of sewage containing polyacrylamide, comprises (i) inoculating HWB-I and HWB-IV strain into lysogeny broth culture medium, centrifuging, using sterilized water to dilute precipitate to obtain HWB-I and HWB-IV activated bacterial solution, (ii) preparing HWB mixed agent, (iii) taking activated sludge, and adding into sequencing batch reactor (SBR), (iv) operating SBR reactor for every cycle, increasing concentration of PAM, and (v) adding HWB mixed agent to SBR reactor, controlling e.g. dissolved oxygen concentration, and operating to complete the process.    USE - Used as a bio-agent combined treating method of sewage containing polyacrylamide.    ADVANTAGE - The method can achieve PAM removal rate of 55-65% after adding HWB mixed agent to the SBR; and can achieve PAM removal rate of 70-75% after adding HWB mixed agent to the bio-contact oxidation reactor.    DETAILED DESCRIPTION - Bio-agent combined treating method of sewage containing polyacrylamide, comprises (i) inoculating HWB-I and HWB-IV strain, respectively into lysogeny broth culture medium, activating for 24 hours at 28 degrees C, centrifuging for 5 minutes at 4000 revolutions/minute, discarding the supernatant, using sterilized water to respectively dilute the precipitate to 10 days to obtain HWB-I and HWB-IV activated bacterial solution, (ii) pouring polyacrylamide (PAM) culture medium (100 ml) to a 250 ml conical flask, then adding HWB-I activated bacterial solution (1 ml) and HWB-IV activated bacterial solution (1 ml), culturing for 24 hours under conditions of 30 degrees C and rotation speed of 140 revolutions/minute of shaker to obtain HWB mixed agent, (iii) taking activated sludge of the domestic sewage plant, adding into the sequencing batch reactor (SBR), controlling the concentration of sludge to 2000 mg/l, using domestic sewage as inlet water, adding PAM until the concentration is 20 mg/l and chemical oxygen demand (COD) is 200-300 mg/l, (iv) operating SBR reactor for every cycle, increasing the concentration of PAM by 20 mg/l until it reaches 100 mg/l, then operating for 20 days, and (v) adding the HWB mixed agent to the SBR reactor according to the reaction volume of 80 OD/l, controlling dissolved oxygen concentration to 2-3 mg/l, pH to 6.5-8, PAM concentration to 100-150 mg/l, and sludge concentration to 1500-2000 mg/l, operating for 45 days to complete the treatment process, where in the step (i), the HWB-I strain is Bacillus cereus (CGMCC NO: 4125); and the HWB-IV strain is Stenotrophomonas acidaminiphila (CGMCC NO: 4124). The PAM culture medium comprises PAM (0.1 g), dipotassium hydrogen phosphate (0.25 g), potassium dihydrogen phosphate (0.25 g), magnesium sulfate heptahydrate (0.2 g), sodium chloride (0.1 g), microelement (1 ml) and distilled water, which is added to make up the volume to 1000 ml. The microelement comprises manganese sulfate (33.9 mg), zinc sulfate monohydrate (42.8 mg), ammonium molybdenum oxide monohydrate of formula ((NH3)MoO24.H2O (34.7 mg) and distilled water, which is added to make up the volume to 1000 ml. The operating conditions for SBR reactor is: water inlet time of 0.5 hours, aeration time of 70 hours, precipitating time of 2 hours, and water discharge time of 0.5 hours.