This study established the first dynamic single-cell transcriptomic landscape of mouse cochlear aging in which identified 27 diverse cell types across five different timepoints. Pairwise differential expression analysis demonstrated that age-dependent changes arise at two months, augment at five months and persist through 15 months, suggesting both early onset and progressive age-related exacerbation. More importantly, age-dependent dynamic gene expression alterations pinpointed loss of proteostasis and elevated apoptosis as hallmark features of cochlear aging and identified intermediate cells localized at the stria vascularis (SV) as the cell type most affected by aging. Mechanistic study indicated that upregulation of ER chaperon protein Hsp90aa1 may be targeted to relieve age-associated decay of stria vascularis. This research provides a wealth of resources for revealing the heterogeneity of human skin stem cells and developing treatment strategies for aging-related hearing loss.