Rhodococcus erythropolis was selected to produce bioflocculant by using slaughter wastewater and the bioflocculant was applied to improve the sludge dewaterability by compared with chemical conditioners.And then,response surface methodology (RSM) was employed to optimize the process of sludge dewatering by the complex of PAC and bioflocculant.Results showed that the bioflocculant showed good performances in sludge dewatering,after conditioned by this bioflocculant with its optimal dose of 12g/(kg DS) and pH value of 7.5,DS and SRF reached 19.8% and 4.6×10¹²m/kg,respectively,which were much better than the ones obtained with Al₃(SO₄)₂ and FeCl₃,but poorer than PAC and PAM.When PAC was used as conditioner,DS and SRF was appeared as 20.1% and 4.5×10¹²m/kg,respectively.DS and SRF were settled as the target responses in the experiments designed by RSM.As the determination coefficients (R²) of 0.9545 and 0.9776,the two quadratic models could agree with experimental data well.Results showed that the optimal conditions for sludge dewatering were bioflocculant dose of 10.5g/(kg DS),PAC dose of 12.4g/(kg DS),and pH value of 7.5,under this optimal condition,DS and SRF appeared as 24.1% and 3.0×10¹²m/kg,respectively.From a practical standpoint,without pH adjustment,DS and SRF were 23.6% and 3.2×10¹²m/kg,respectively.The above results were better than the alone using of bioflocculant or PAC in sludge dewatering.