[Objective] This study aims to quantify the effects of climate change and human activities on carbon sequestration in the terrestrial ecosystems of the Qinghai Lake basin, providing a scientific basis for assessing carbon sequestration capacity of regional vegetation, formulating climate change response measures, and implementing ecological restoration.[Methods] Based on MODIS remote sensing data, net ecosystem productivity（NEP） was estimated. Trend analysis, stability analysis, Hurst index, and center migration methods were employed to investigate the spatiotemporal patterns and evolution trends of NEP in the Qinghai Lake basin from 2000 to 2021. Partial correlation, multiple correlation, and residual analysis were used to quantitatively separate the effects of human activities and climate change on spatiotemporal differentiation of NEP. [Results] 1) Over the 22-year period, NEP in the Qinghai Lake Basin showed an increasing trend at a rate of 2.16 g/（m²·a）, with a spatial distribution pattern of higher values in the southeast and lower in the northwest, radiating outward from Qinghai Lake with diminishing intensity. Nearly 80% of the area exhibited an upward NEP trend, with extremely significant and significant increases accounting for 61.50% and 17.61%, respectively. Areas with declining NEP trends were distributed along the western, northern, and northeastern shores of Qinghai Lake, with sporadic occurrences in the northern part of the basin. Approximately 77.32% of the basin exhibited low and extremely low volatility in NEP changes, while 89.19% of the areas with increasing NEP were projected to shift to a decreasing trend in the future. The center of carbon sources generally migrated from the northwest to the southeastern shore of Qinghai Lake, covering a straight-line distance of about 171.72 km, whereas the center of carbon sinks shifted westward by approximately 2.68 km. 2) The average partial correlation coefficients between interannual NEP changes and temperature, precipitation, solar radiation, and land surface temperature were 0.141 3, 0.124 7,-0.182 9 and-0.002 2, respectively. Temperature and precipitation showed positive correlations with NEP, while solar radiation and land surface temperature exhibited negative correlations. All correlations were statistically insignificant. 3) Residual analysis indicated that regions where both climate change and human activities jointly promoted NEP increases accounted for 95.10% of the study area. [Conclusion] Climate and human activities jointly affect NEP changes. Over the past two decades, most areas of the Qinghai Lake Basin’s terrestrial ecosystem have seen a notable increase in carbon sink capacity. Under a warmer and wetter climate background, ecological measures in Qinghai Province-such as grazing prohibition, desertification control, and afforestation-have collectively boosted NEP growth. However, increasing human activities, frequent construction projects, and the rising water level and expanding area of Qinghai Lake may hinder further NEP improvement.