[Objective] The effects of different fertilization modes on the vegetation diversity, development, and stability of soil aggregates and recovery of the organic carbon pool under a sea buckthorn forest were studied in order to provide a basis for the reconstructing of open-pit mine vegetation, improving soil quality, and recovering the aggregate carbon pool. [Methods] The study was conducted on the sea buckthorn demonstration base at a dumpsite of an open-pit mine of Heidaigou, Inner Mongolia. We analyzed the effects of the combined action of fertilizer modes such as inoculation with arbuscular mycorrhizal fungi (AMF) and other treatments (added weathered coal and green fertilizer) on the stability of soil aggregates and organic carbon recovery in the early vegetation restoration area of the open-pit mine dumpsite by investigating vegetation populations and collecting soil aggregate samples. [Results] Under the six fertilizer treatment modes, the experimental group inoculated with AMF, applied green fertilizer, and added weathered coal (sand, green, wind) had the best effect on the improvement of understory vegetation diversity, and the diversity index was significantly improved compared with the control treatment. The experimental group inoculated with AMF and applied with green fertilizer (sand, green) had the most significant effect on the development and stability of aggregates. The analysis of the effect of organic carbon and total nitrogen in aggregates showed that the organic carbon and total nitrogen in aggregates for the sand and green treatments were significantly higher than those in the experimental group inoculated only with AMF. [Conclusion] Different fertilization modes had positive effects on vegetation diversity, soil aggregate development, stability, and organic carbon pool restoration under sea buckthorn forest. Inoculation with AMF, application of green fertilizer, and added weathered coal should be used to increase the content of soil organic carbon and to promote the development of aggregates during vegetation reconstruction in open-pit mine dumpsites.