A bioflocculant was produced by using rice stover, and its performance in the improvement of sludge dewatering was investigated, further, response surface methodology (RSM) was employed to optimize the treatment of sludge dewatering by the composite of the bioflocculant and Polyaluminum chloride (PAC). Optimal culture conditions for bioflocculant production were determined as 4g K₂HPO₄, 2g KH₂PO₄, 0.2g MgSO₄, 0.1g NaCl, and 2g urea dissolved in a mixture of 800mL distilled water and 200mL rice stover acid hydrolyzate, and the corresponding bioflocculant yield reached 0.96g/L. Keep original pH value of the sludge, when bioflocculant dose was adjusted at 12mg/L, DS improved 59.5%, and SRF reduced 53.6%, which indicated that the sludge dewatering has been significantly improved after treated by the bioflocculant. In the same manner, when the sludge was treated by 3g/L PAC, DS increased to 16.4% and SRF decreased to 5.4×10¹²m/kg, compared to that of 13.2% and 11.3×10¹²m/kg of the original sludge, the sludge dewatering was significantly improved. Optimal conditions for sludge dewatering by the composite of the bioflocculant and PAC were bioflocculant dose of 8mg/L, PAC dose of 1.9g/L, and pH=8.0, under this optimal condition, DS and SRF appeared as 24.1% and 3.0×10¹²m/kg, respectively. From a practical standpoint, without pH adjustment, under the optimal condition of bioflocculant dose of 8.1mg/L, PAC dose of 1.9g/L, and natural pH value of 6.4, 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.