To research the timing of the breeding population and juveniles of Coilia nasus into or out of the Poyang Lake in the early period of the fishing ban, support the conservation of the resources and identification of the habitat of Coilia nasus in Poyang Lake, a fixed station was set up in the Hukou region during its fishing season from April to October in 2023. The resource dynamics of the breeding population in the lake and juveniles out of the lake were tracked and monitored. Both the timing and the environmental impact factors were then analyzed. In terms of the breeding population in the lake, the range of quantity caught per unit from April to July was 19~971 ind./(1000 m² ·h), with an average of (294±201) ind./(1000 m² ·h). Correspondingly, the range of weight caught per unit was 0.83~84.25 kg/(1000 m² ·h), with an average of (25.92±18.10) kg/(1000 m² ·h). The range of body length was 150.6~382.1 mm, with an average of (298.2±29.1) mm. The range of body weight was 10.6~238.1 g, with an average of (89.9±29.8) g. The ratio of male to female was 2.2 : 1, and the proportion of gonadal development from Stage I to V was in the order of 0.09%, 46.01%, 38.00%, 13.84%, and 2.06%. The results showed that May was the peak period for the breeding population moving into the lake. The mean values of quantity and weight caught per unit were (514±168) ind./(1000 m² ·h) and (47.04±16.08) kg/(1000 m² h), respectively. These were significantly higher than those of other months (P＜0.01). The body length and body weight decreased significantly along with the migration during the fishing season (P＜0.01). The maximum of the average body length occurred in May (301.5±26.4) mm, and the minimum was recorded in July (292.2±30.6) mm. For body weight, the maximum and minimum were in April (98.5±34.0) g and July (82.0±25.2) g, respectively. In the same period, the proportion of females continued to increase, and males decreased. For gonadal development, the proportion of individuals for Stage II decreased from 81.14% in April to 22.22% in July and increased from 18.77% in April to 77.78% in July for Stage III. In terms of the population moving out of the lake, the range of quantity caught per unit was 11~8571 ind./(1000 m2 ·h) from July to October, with an average of (1316± 1908) ind./(1000 m² ·h). Timing showed that the peak period was in July and September, and the mean value of quantity caught per unit in July was (2845±2940) ind./(1000 m² ·h), followed by September (1769± 1862) ind./(1000 m² ·h)). Meanwhile, the minimum of the average quantity caught per unit was (285±327) ind./(1000 m² ·h) in October. Environmental factors analysis showed that the quantity caught per unit for the juvenile population out of Poyang Lake was consistent with the trend of water level difference. The results show that the fishing season of Coilia nasus in Poyang Lake was advanced, and the duration was prolonged. Furthermore, the miniaturization of the population improved, and the resource recovery was substantial.