Sea ice export through the Fram Strait is crucial in the dynamic evolution of Arctic sea ice and can further modulate Arctic sea ice mass balance as well as the ocean thermohaline circulation. In this study, based on model outputs from a parameter-optimized and fully physical ocean-sea ice coupled model and sea ice age observation, we estimate sea ice volume (SIV) flux and its age evolution via the Fram Strait. The estimate of mean annual SIV flux is about 1605±315 km³/yr (1979-2021) without a significant trend in the study period. Combining with sea ice age dataset, the variation of sea ice age and its corresponding SIV flux on the Fram Strait are obtained for 1984-2020. Our results indicate that although the annual SIV flux through the Fram Strait changes insignificantly on a long-term scale, the outflowing sea ice through the Fram Strait is becoming younger. The SIV flux of 1st-year ice significantly increases among 1984-2020 as we expected, but SIV fluxes of different compositions in the multi-year ice (MYI) present diverse variations. The proportions of 2nd-year ice and 3rd-year ice fluxes in the annual SIV flux increase extremely from 6.8% and 25.0% in the 1980s to 49.0% and 38.8% in the 2010s, respectively, while the proportions of 4th-year ice and 5+ year ice significantly decrease from 22.8% and 45.0% in the 1980s to 7.1% and 1.6% in the 2010s, respectively. Additionally, the annually prevailing sea ice age of MYI on the Fram Strait also in the SIV flux through the gate obviously transforms from 4th-year ice and 5+ year ice to 2nd-year ice and 3rd-year ice around 2007/2008. The results are beneficial to promote the understanding of the changes in SIV export through the Fram Strait under the warming Arctic.