Opencast coal mining causes serious damage to the natural landscape, resulting in the depletion of the carbon sequestration capacity in the mining activity. There are few studies on the variation of carbon sequestration capabilities caused by land use changes in opencast mining areas. This paper uses six images were used to quantify the changes in land use types from 1986 to 2015 in the Pingshuo mining area in northwest China. At the same time, used statistical analysis and mathematical models to study soil and vegetation carbon sequestration. Results indicate that the total carbon sequestration exhibits a significant downward trend from 4.58 × 106 Mg in 1986 to 3.78 × 106 Mg in 2015, with the decrease of soil carbon sequestration accounting for the largest proportion. The carbon sequestration of arable land accounted for 51% of the total carbon sequestration in the mining area, followed by grassland (31%) and forestland (18%). Land reclamation contributed to the greatest increase in carbon sequestration of arable land from 17,890.15 Mg (1986) to 27,837.95 Mg (2015). Additionally, the downward trend in the carbon sequestration capacity of the mining ecosystem was mitigated after 2010 as the positive effects of land reclamation gradually amplified over time and as the mining techniques were greatly optimized in recent years in the Pingshuo mining area. Thus, terrestrial carbon sequestration can be improved through land reclamation projects and optimized mining activities. These results can help guide the utilization of reclaimed land in the future.