In ovarian follicle development, estrogen acts as a regulatory molecule to mediate proliferation and differentiation of follicular cells. ER alpha (estrogen receptor alpha) exerts regulatory function classically by binding directly to the estrogen response element, recruiting co-factors and activating or repressing transcription in response to E2. In this study, we used ChIP-seq to map ER alpha-binding sites in ovaries of Hy-line Brown commercial hens at 45 d, 90 d and 160 d. In total, 24,886, 21,680 and 23,348 binding sites were identified in the ovaries of hens at 45 d, 90 d and 160 d, which are linked to 86, 83 and 74 genes, respectively. The PPI network contains 47 protein nodes and 164 interaction edges, among which, AKT1 (V-Akt Murine Thymoma Viral Oncogene Homolog 1) and ACTN2 (Actinin Alpha 2) with the highest weight in the network, followed by CREB1 (CAMP Responsive Element Binding Protein 1), and EPHA5 (EPH Receptor A5) were identified. These genes are likely related to sexual maturity in hens. This study also provides insight into the regulation of the ER alpha target gene networks and a reference for understanding ER alpha-regulated transcription.