To improve the dewaterability of residual sludge and increase the dosage of flocculant, the residual sludge from one sewage treatment plant was studied by analyzing the impact of combination of microwave pretreatment technology and PAM on the sludge dewawtering. The results showed that proper coupling technique could improve the effect of sludge dewatering considerably compared to PAM. There was significantly decrease in the value of sludge’s tcs, sludge’s water content after centrifugation and sludge’s specific resistance, from 37.3 s,83.68％,1.72×10⁹ s²·g-1 (only by PAM) to 16.7 s,78.16％,0.35×10⁹ s²·g-1, and the dosage of PAM reduced by about 33％. Appropriate combination of microwave and PAM could improve the sludge dewatering significantly.