Background <p>Energy allocation between reproduction and survival represents a fundamental life-history challenge for animals in seasonal environments. Using integrated transcriptomics and metabolomics, we investigated <i>Nanorana taihangnica</i> (Anura: Dicroglossidae), a non-amplexus stream frog endemic to China, to elucidate the seasonal morphological and molecular coordination between the testis and abdominal fat body.</p> Results <p>Morphological analysis showed that fat body adipocyte cross-sectional area minimized at the end of the breeding season but rapidly recovered thereafter, while testicular volume continued declining post-breeding and only recovered during the non-breeding period. During breeding season, multi-omics analyses revealed that the fat body enhanced fatty acid oxidation, upregulated histidine-carnosine metabolism, activated NAD⁺ metabolism and FOXO3-mediated antioxidative responses to mitigate metabolic stress, and regulated adipocyte survival and apoptosis via sphingolipid signaling. Seasonal testicular development was centrally regulated by the mTOR signaling pathway, whose activity integrated autophagy levels, NAD⁺ availability, and aspartate metabolism to coordinate spermatogonial proliferation and spermatogenesis.</p> Conclusions <p>This study demonstrates that <i>N. taihangnica</i> optimizes seasonal energy storage, allocation, and reproductive investment through molecular and metabolic crosstalk between the fat body and testis, providing empirical insights into the physiological integration of life-history strategies in animals inhabiting fluctuating environments.</p>