Taking some analog sewages containing polymer as study subjects, the effects on chemical oxidation and flocculating of the sewages under different reaction conditions was studied. The turbidity of the supernatant was tested and analyzed by turbidity meter, the microstructure of flocs was observed by image analyzers and the fractal dimension was calculated by perimeter-size method; the PAM concentration was tested by starch-cadmium iodide method, then PAM removal rate was calculated. The results showed that there was a negative correlation between the fractal dimension of flocs and the turbidity of supernatant, so the fractal dimension of flocs could represent the effects of flocculation and sedimentation in electric-Fenton treatment. The PAM removal rate and the fractal dimension of flocs showed different rules in various reaction conditions; hence, it was more reasonable to adjust the test conditions on the basis of these rules. Under optimal reaction condition of pH value of 2.6, FeSO4 dosage of 130 mg/L, H2O2 dosage of 1 ml/L, electric current density of 25 mA/cm2, and the PAM removal rate was 95.34%, the fractal dimension of flocs was 1.8438 and the subsiding time was 26 min.