Abstract: Curdlan is a water insoluble exopolysaceharide produced by bacteria under nitrogen- limiting conditions.Curdlan production is great impacted by distribution ratio for each group of fermentation medium wall.Thus optimization of fermentation medium is important to curdlan production.The fermentation medium of curdlan were optimized by the response surface methodology.First, Plackett-Burman design was adopted to screen out the important factors affecting the output of curdlan:sucrose, (NH4) 2 HPO4, MgSO4 and corn syrup.Then the path of the steepest ascent was utilized to approach the optimal region.At last, the optimized medium was obtained by Box-Behnken design and response surface methodology.Under the condition (sucrose 61g/L、 MgSO4 1g/L, corn syrup 2.5mL/L, (NH4) 2 HPO4 2.4g/L, KH2 PO4 1.4g/L, CaCO3 1.4g/L) , the result of fermentation (47.73g/L) was increased by about 35.6% compared with the previous condition (35.2g/L) .