To detect the reproductive characteristics and condition status of Coilia mystus (Linnaeus)in the Changjiang River estuary, a total of 2 138 specimen were collected during breeding season in 2005, 2006, 2008 and 2009, and the biological parameters of C.mystus including body length, body weight, gonad weight, liver weight, fecundity etc. were measured. The results showed that (1) Body length of the samples ranged from 61.2 to 195.0mm,body weight ranged from 2.1 to 32.7 g; and female weighted more than male, especially in the years of 2008 and 2009. The weight difference between male and female became greater with the increasing of body length. The growth rates were different among years,with the lowest value in 2006. (2) There were close relationship between the reproductive capacity and the body length and body weight. The gonad development was the best in 2005, and the worst in 2006. (3)Liver weight of the samples showed positive correlation with the body length and body weight, and there were dimorphism between the sexes: the liver weight of female weighted more than male of the same body length. The condition factor(K) of the C.mystus showed the same trend in both sexes and the smallest condition factor was found in 2006; no apparent variations were observed in other years. There were also no significant difference between fat body weight and fat index between the sexes. In other words, the population of the C.mystus had higher condition factor (K), greater body length and body weight, yet lighter gonad in 2006. The year of 2006 experienced less river discharge and higher temperatures than many former years. While 2005 was the second warmest year in history record, and the samples showed slow growth, good condition ingonad instead, and condition factor did not decrease rapidly. In conclusion, the reproductive characteristics and body condition of the short life species C. mystus varied greatly in different years, which may be caused by yearly weather changes in the Changjiang River estuary.