Abstract: In order to better understand the regional characteristics of reducing sugar content in Hunan flue-cured tobacco and make clear the correlation between reducing sugar content and smoking quality,the reducing sugar contents in B2F,C3F,X2F sampled from main tobacco planting areas in Hunan Province were determined by autoanalyzer and their smoking quality was quantitatively assessed.The spatial distribution and basic statistical characteristic of reducing sugar content,the content difference between stalk positions,cultivars,crop years,grown areas and ecological regions,and relationship between reducing sugar content and smoking quality indexes were quantitatively studied with basic statistics and geostatistical analysis.The results showed that:the reducing sugar contents in most samples were within a reasonable range while slightly higher in a few samples.The contents in tobacco of different grades and crop years differed extremely significantly,statistical difference only observed in C3F and X2F grades in 3 prevalent cultivars,significant difference only found in B2F and C3F grades of tobacco from different grown areas and ecological regions;there was different spatial distribution of reducing sugar contents in B2F,C3F and X2F.The reducing sugar content was linearly correlated with evaluation scores of aroma quantity,offensive odor,concentration,irritation and aftertaste;and curvilinearly correlated with aroma quality,strength,flavor,taste and total evaluation scores.When reducing sugar content was from 22.00% to 24.00%,tobacco presented good flavor and taste;and when it was 23.00%,the smoking quality was excellent.