We investigated the effect of photoperiod on performance, ovarian morphology, reproductive hormones levels, and their receptors mRNA expressions in laying ducks. After adaption, 300 252-day-old Jinding laying ducks were randomly allocated to 5 groups, receiving 12L:12D, 14L:10D, 16L:8D, 18L:6D, or 20L:4D, respectively. Each treatment had 6 replicates of 10 birds each. The feeding trial lasted 8 wk. Egg production, egg mass, and ADFI increased linearly and quadratically with increasing photoperiods (
P
< 0.05), and the higher values of them occurred in photoperiods ≥ 16 h, compared with 12L:12D (
P
> 0.05). Initial and bare stroma weight increased quadratically, while total large white follicle (
LWF
) number and weight increased linearly and quadratically, with increasing photoperiods (
P
< 0.05). The higher values of them occurred in 16L:8D and 18L:6D treatments as well as the higher total LWF weight also occurred in 20L:4D, compared with 12L:12D (
P
> 0.05). Besides, 16.93 and 16.93 h were the optimal photoperiods for bare stroma (follicles ≥ 2 mm in diameter removed) weight and total LWF weight, respectively, calculated from reliable regression equations (
R
2
≥ 0.5071). Compared with 12L:12D, the higher levels of estradiol, progesterone, follicle-stimulating hormone (
FSH
) as well as the higher expressions of estrogen, luteinizing hormone (
LH
) and progesterone receptors were observed in ≥16 h photoperiods (
P
< 0.05), while the higher LH level and FSH receptor expression only occurred in 16L:8D and 18L:6D (
P
< 0.05). In the hypothalamus, higher mRNA expression of gonadotropin-releasing hormone occurred in 16L:8D and 18L:6D groups (
P
< 0.05). Meanwhile, gonadotropin-inhibitory hormone and prolactin increased in 20-hour photoperiod (
P
< 0.05), and the latter may be due to theup-regulation of vasoactive intestinal peptide expression (
P
< 0.05). To sum up, an appropriate photoperiod could improve the performance and reproductive organ and ovarian follicles development through reproductive hormones and their receptors, and 16.56 to 10.93 h is an adequate photoperiod for laying ducks.