Abstract: In order to explore the change trend and influencing factors of organic carbon reserves in the ground substrate, ground substrate organic carbon reserves of Xinle City were calculated according to the classification method of ground substrate types using the data of Xinle City in 2005 and 2021, and the change trend and determining factors of Xinle City′s ground substrate organic carbon reserves were analyzed. The results showed that, from 2005 to 2021, the total storage of organic carbon in the ground substrate of Xinle City showed an increasing trend; The average organic carbon content and unit substrate carbon content in the surface layer were negatively correlated with the substrate particle size; The growth rate of the average organic carbon content in the surface layer（0-0.2 m） was negatively correlated with the size of the substrate particle size; The growth rate of the average organic carbon content in the deep layer（2.0 m） was positively correlated with the size of the substrate particle size. The total storage of organic carbon in ground substrate in Xinle City was on the increase trend, and the main factor for the decrease of organic carbon storage in coarse soil was the destruction of ground substrate and the loss of organic carbon caused by sand mining in river channels.The main factors for the increase of organic carbon storage in sandy soil and loam were afforestation and reasonable agricultural activities.