Abstract: The content of sugar in Bletilla striata was very important to evaluate its quality. Therefore,quantitative detection methods of 4 sugars were studied in this paper. Bletilla striata powder was mixed with distilled water uniformly,absolute alcohol was added to mixture and the volume fraction of alcohol was 80%. Mixture was extracted by ultrasound and centrifuged. After removal of alcohol from upper,the liquid was diluted to required volume with distilled water.The content of reducing sugar and non-reducing oligosaccharide after acid hydrolysis were quantitative detected by GB5009.7. After amylase hydrolysis of solids,diluted to required volume with distilled water and centrifuged. 4 times volume of absolute alcohol was added to upper clear liquid,mixed uniformly and centrifuged. Starch was detected in centrifuged clear liquid by GB5009.9. Rude polysaccharide was detected in solid by SN/T 4260. Results showed that,the RSD(relative standard deviation)experiment result of reducing sugar,non-reducing oligosaccharide,starch and rude polysaccharide were 1.12%,0.67%,3.66%,1.73%,recovery rate were 103.41(98.14)%,93.76%,101.21%,96.16%. The content of reducing sugar,non-reducing oligosaccharide,starch and rude polysaccharide was 1.37%,4.46%,4.70%,42.50% in Bletilla striata sample. The accuracy and precision of this method conformed to related national quantitative detection standards of carbohydrate and could be used for quantitative detected 4 carbohydrates in Bletilla striata.