A stain RH214 with high ability to produce pectinase was isolated from soil and identified as Bacillus smithii.In order to improve the production of pectinase,some fermentation conditions were optimized.According to single-factor experiments,the optimal carbon source,nitrogen source and salt were determined to be soluble starch,peptone,and KH2PO4 respectively.As the key factors,these single factors(soluble starch,peptone and KH2PO4) were further optimized by Box-Behnken design and response surface methodology.A maximum pectinase activity of(88 ±0.86) U/mL was obtained using the condition as follows: after 16 h fermentation of 80 mL fermentation medium containing soluble starch 85.6 g/L,peptone 11.8 g /100 mL,KH2PO43.8 g/L and FeSO41 g/L,KCl 0.5 g/L at an initial pH of 9.0,fermentation temperat.ure 40℃ with 150 r/min shaking.Under these conditions,the activity production was 4.3 times higher than the initial production(20.50 U/mL) before optimization.