The two filamentous fungi of Mucor circinelloides XY-Z and Penicillium oxalicum LY-1 isolated from citric acid wastewater sludge collectively enhanced sludge dewaterability by 85.83% to achieve the lowest value of normalized sludge specific resistance (SRF) to 6.8 × 10¹¹ m·L/kg·g-TSS. The results showed that 75.77% of slime extracellular polymeric substances (EPS), 42.99% of protein in slime EPS and 60.27% of polysaccharide in LB-EPS were degraded during activated sludge treatment by the two mixed fungi of Mucor circinelloides XY-Z and Penicillium oxalicum LY-1, contributing to the conversion of 64.61% of bound water wrapped in EPS into free water, thereby improving activated sludge dewaterability.