Coilia nasus is one of the most important commercial anadromous spawning fishes in Yangtze River.In this study we analyzed the age structure and body length on 299 specimens collected at three localities,Jiuduansha (JDS) in Shanghai City,Jingjiang (JJ) in Jiangsu Province,Wuhu (WH) in Anhui Province,from April to May 2009.The results showed that the body length (BL) of C.nasus were 15.8 to 32.8 cm (average 23.3±3.5 cm),52.51% of the specimens were between 18.0 and 24.0 cm.The body weight (BW) varied from 11.83 to 143.80 g with average of 48.19±24.89 g, 59.53% of them weighted from 10.00 to 50.00 g.The body length and body weight of WH population was smallest (ANOVA, P=0.000<0.01). The 299 specimens were aged in 4 classes. Of 51.28% and 53.97% of specimens in JDS and JJ population were aged at 3, respectively. In contract,85.26% of specimen in WH population was aged at 2. Compared to the fishes harvested in 1970s, in the same section in Yangtze River, the values of BL, BW and age of the studied specimens were declined dramatically.The overall sex ratio (♀:♂) was 1:1.57,however, the sex ratio varied between populations, i.e. 1:1.28 for JDS population, 1:1.46 for JJ population and 1:1.97 for WH population, indicated a gradually increase trend of sex ratio along Yangtze River upwards.The average fatness of all specimens were 0.35±0.05,and the maximum value was recorded in JJ population in specimen with same age.The higher fatness of JJ population may explain why fish C.nasus harvested in JJ had a highest commercially value.