Global carbon sequestration and release has been a hotspot issue concerning people's livelihood in recent years. The importance of regional carbon sequestration and release to the ecological environment was self-evident. It is of great theoretical and practical significance to use remote sensing data and appropriate estimation model to quantitatively estimate NPP (Net Primary Productivity) and analyze spatio-temporal pattern of vegetation carbon sequestration and carbon release in the Loess Plateau. Based on the CASA (Carnegie Ames Stanford Approach) model, this paper estimated the annual change of the NPP on the loess plateau from 1990 to 2015, and analyzed the comprehensive effects in the process of Land Use/Land Cover Change (LUCC), elevations and their synergistic effects. It found that:(1) vegetation NPP and carbon sequestration showed an increasing trend in the Loess Plateau from 1990 to 2015. The annual average growth rate of NPP was 2.74 gC m^-2 a^-1 and the annual average growth rate of carbon sequestration was 1.13 TgC/a. The average annual NPP (619.5 gC m^-2 a^-1) of forest land in the study area was much higher than that of other land types, which was an ideal means of carbon sequestration. (2) The annual mean NPP of the Loess Plateau increased year by year, but the annual mean annual NPP decreased first and then increased with the increase of elevation, while the annual total NPP and carbon sequestration showed opposite trends with the increase of elevation. (3) In the study area, conversion of cropland to forest contributed the most to vegetation carbon sequestration among all land use changes types, meanwhile, the conversion of forest into cropland or grassland could not achieve carbon sequestration. In addition, it is recommended to convert grassland to cropland when the elevation is lower than 1500 m, return cropland to grassland when the elevation is higher than 1500 m, and convert cropland and grassland to forest when the elevation is higher than 3000 m in the study area. The study focuses on the effect of carbon sequestration under the synergistic effect of land use change and elevations. It is concluded that the development and utilization of land in the study area leads to the increase of carbon sequestration, while the ecological return of land leads to the increase of carbon sequestration; Moreover, it is more suitable to convert cropland to forest at low and high altitude regions than at middle altitude in the study area, in order to provide reference and guidance for the ecological environment in the regional scale.