Accurate assessment of wetland ecosystem carbon sinks is an estimation of future atmospheric CO2 concentrations, prediction of climate change and its impact on wetland ecosystems. In this study, using remote sensing data and 351 wetland sample sites in 2015, a remote sensing multiple linear regression model (RS-MLRM) was constructed to clarify the carbon storage capacity and its changing process from 2000 to 2015 and their controlling factors in arid regions wetlands. The results are as follows: (1) The studied wetlands acted as atmospheric carbon sinks from 2000 to 2015, increasing by 3.88 × 104 tC/a. Moreover, the soil carbon sink (0–40 cm) was approximately twice that of the vegetation carbon sink. (2) Carbon sinks had a clear spatial distribution, with high concentrations in Helan and Pingluo Counties in the central Ningxia Plain. From 2005 to 2015, constructed wetlands significantly increased the carbon sink (P < 0.05) and were the main contributors to carbon sequestration, indicating that positive human intervention enhances the carbon sink effect of wetlands. (3) Human activities, policy factors, soil physical and chemical properties and nutrients were the main factors affecting carbon sink in Ningxia Plain Wetland in arid regions. (4) The results provides a scientific basis for the protection and management of wetland ecosystems in arid areas. Display omitted •We estimate carbon sinks in Ningxia Plain Wetland in arid areas.•We develop an accurate and applicable RS-MLRM for estimating carbon sinks.•Wetland carbon density increased significantly in Ningxia Plain from 2000 to 2015.•Human activity, policy were the main factors affecting carbon sink in arid areas.•These findings related to carbon cycling and environmental controls in arid areas.