[Purpose] The effect of the forest carbon sequestration plays a crucial role in responding to global warming and regulating the regional carbon cycle. Accounting the value of forest carbon sequestration and exploring the path of ecological product value realization has a significant influence on coordinated economic-ecological development. [Method] The 12 league cities in Inner Mongolia were taken as the study area, and the period from 2009 to 2023 was taken as the study period. A multi-metric framework integrating the carbon sequestration rate method, optimal pricing method, carbon tax method, and afforestation cost method for CO2 fixation was developed to quantify forest carbon sinks and their spatiotemporal value dynamics. A hybrid analytical framework combining multiple regression models and grey relational analysis is also constructed to quantify the determinants of value and their synergistic effects, with the aim of identifying scalable mechanisms for monetizing forest carbon sink ecological products. [Consequence] ①The forest carbon sink of all league cities in Inner Mongolia has achieved significant growth, and the most obvious rate is in 2014, with the total increase of 160.00%-200.00%. Wuhai City, Bayan Nur City and Ulanqab City has the rate more than 250.00%, and Ordos more than 50 times. ②The forest carbon sink value across prefecture-level cities exhibited an overall temporal growth trend, with centrally located regions demonstrating the most rapid growth rates. Spatially, it formed an evolution pattern characterized by 'higher values in the east and lower in the west and peaking in the northeast, decreasing from northern and southern extremities toward the center in midland areas, and declining from northwest to southeast in western regions'. ③ Due to the difference of geographical locations, industrial structures, policy orientations and forest age structures between league cities, the influencing factors exhibit significant spatial heterogeneity in both their operational mechanisms and impact intensity. Specifically, Wuhai City, Bayan Nur City, Hinggan League, and Hulunbuir City demonstrate stronger inter-factor correlations, while Alxa League, Hohhot City, and Chifeng City show relatively weaker associations among factors. The main influencing factors include economic development, precipitation, forestry output value, forest coverage and scale of forest investment. [Conclusion] This paper proposes the path to realize the value of forest carbon sequestration products in Inner Mongolia: Addressing the quantification challenges of ecological products by establishing a scientific valuation framework; enhancing the primary productivity of forest resources and institutionalizing full-cycle management mechanisms; developing region-specific supporting institutions for forest carbon sink industries and eco-product development, while exploring diversified value realization models adapted to regional disparities. The findings provide critical references and practical insights for unraveling the intrinsic mechanisms underlying forest carbon sink value dynamics, thereby advancing sustainable management and value realization of forest ecological products.