Accurate estimation of carbon storage and carbon density of a single category of forest is an important basis for studying regional forest carbon storage. Pinus sylvestris var. mongolica (MP) natural forests were selected as the object of this study, and a new method for estimating MP stand structure was established based on the combination of inventory data, ground survey data and multisource remote sensing data. Based on the method, we estimated the carbon storage and carbon density of MP forests in the natural concentrated distribution region (the region of Honghuaerji Forestry Bureau under the jurisdiction of Inner Mongolia). Finally, the topographic features of carbon storage and carbon density of MP forests were discussed in combination with topographic features. The results showed that there was a significant linear relationship between diameter at breast height and Tasseled Cap Greenness of Landsat8 OLI. The area of the natural MP forests in the study region was 70923.30 hm² in 2016, the aboveground (stem, branch and leaf) carbon storage was 3.91 Tg C, and average carbon density was 55.18 t·hm^-2 (10.26-148.75 t·hm^-2). Influenced by human interference and natural elements, the carbon storage and carbon density increased first and then decreased with increasing altitude, whereas it decreased with increasing slope. The maximum carbon density occurred on the sunny slope and the minimum value was located on the shade slope due to the heliophilous characteristics for the MP. According to the spatial distribution characteristics of carbon storage and carbon density, subregionspecific management can significantly improve carbon sink.