Objective: The development of pre-hierarchical follicles (PHFs), especially small yellow follicles (SYFs), directly affects the recruitment of dominant follicles and subsequently affects the egg-laying performance of chickens. The development of PHFs, especially SYFs, and their regulatory mechanisms remain unclear.Methods: Transcriptomic and metabolomic analyses were conducted on large white follicles (LWFs) and SYFs in chickens.Results: Transcriptome sequencing revealed 258 differentially expressed genes (DEGs) between SYFs and LWFs, with 172 genes upregulated and 86 downregulated. The DEGs were mapped to 17 Kyoto encyclopedia of genes and genomes (KEGG) pathways, including glutathione metabolism, ferroptosis, calcium signaling pathway, and neuroactive ligand– receptor interactions, among others. The metabolome analysis revealed 129 significant differential metabolites (DMs), comprising 36 upregulated and 93 downregulated metabolites. The DMs were associated with nine KEGG pathways, including glutathione metabolism, alpha-linolenic acid metabolism, and linoleic acid metabolism, etc. The combined transcriptional and metabolic analysis revealed significantly enriched pathways. Five KEGG pathways associated with follicular development were identified, including glutathione metabolism, ferroptosis, alpha-linolenic acid metabolism, linoleic acid metabolism, and pyrimidine metabolism.Conclusion: Glutathione metabolism may directly inhibit Ferroptosis, which can induce apoptosis of granulosa cells, thereby regulating SYFs development in chickens. These findings could serve as a reference for improving the egg-laying performance of Tengchong snow chickens.