The objective of this work was to improve the yield of pneumocandin B0 (PB0) by optimizing fermentation medium.By Central Composite Design principles and Design Expert 7.0 anal. software, based on the results of orthogonal test, the method of Response Surface Methodol. with 4 factors and 3 levels was adopted on optimizing four main factors which affect the yield of PB0.The maximum response was predicted by Numerical Optimization.The verification test and the scale-up experiment in 20M3 fermenter was carried out.Under the optimum condition, the yield of PB0 was resp. 35% and 38% higher than control in shake flask and in 20M3 fermenter.By Response Surface Methodol., the yield of PB0 was significantly increased, and successfully using in industrial production