The efficient conversion of hemicellulose is a key step in improving the utilization of all components of sweet sorghum bagasse. Sweet sorghum bagasse was pretreated by subcritical hydrolysis. The effects of different reaction temperature (160-200℃) and reaction time (10-60 min) on the yield of xylose(C-5 sugar) and byproducts were investigated by subcritical hydrothermal pretreatment. The experimental conditions were described by intensity factor. The effects of various organic acids on the subcritical hydrolysis of hemicellulose

including acetic acid

lactic acid and acetic acid+lactic acid were further investigated. The results showed that the maximum xylose concentration was 4.79 g·L-1at the severity of 3.96(180℃

40 min)

during the subcritical hydrothermal pretreatment without added acid. The addition of organic acids could enhance the hydrolysis reaction and increase xylose concentration. Compared to the treatment with acetic acid or lactic acid alone

the combined use of acetic acid and lactic acid can effectively promote the degradation of hemicellulose and inhibit the formation of by-products. The maximum xylose concentration was 7.92 g·L-1

which was obtained at 180℃

for 40 min

and with the addition of 1%(mass) acetic acid+lactic acid(lactic acid:acetic acid=6:4).