[Objective] To investigate the variations in vegetation cover in the Qinjiang River Basin and their effects on runoff and sediment load, and to provide scientific support for watershed management and sediment regulation. [Methods] Monthly and annual data series (2000–2021) of runoff, sediment load, NDVI, and precipitation, alongside annual growing-season datasets of NDVI, precipitation, and temperature (2000–2024), were used. Correlation analysis, partial correlation analysis, and multiple linear regression models were applied to analyze the interannual and seasonal variations in vegetation cover and their water–sediment responses, while regression residual analysis was used to explore the driving factors behind vegetation cover change. [Results] ① From 2000 to 2021, vegetation cover in the Qinjiang River Basin showed a continuous improvement, with NDVI exhibiting an increasing trend and a significant negative correlation with sediment load. Multiple linear regression results indicate that vegetation cover and precipitation jointly explain variations in sediment load: an increase of 1 mm in annual precipitation combined with an increase of 0.1 in the annual mean NDVI was associated with a reduction of 3.05×10? t in annual sediment load. ② Seasonal variations in NDVI followed the order of summer > autumn > spring > winter. The regulation of water–sediment processes by vegetation exhibited pronounced seasonal differences. Vegetation showed the strongest sediment retention effect in summer, with a negative correlation between NDVI and sediment load, whereas positive correlations were observed in spring and winter, indicating a distinct seasonal asymmetry in soil and water conservation effects. ③ Climate change and human activities collectively accounted for more than 90% of the total contribution to vegetation cover change. Temperature increase and afforestation were the main drivers of vegetation restoration. The contribution rates were greater in the warmer and wetter mid-lower reaches than in the upper reaches, while urban expansion exerted an inhibitory effect on vegetation cover. [Conclusion] Vegetation restoration in the Qinjiang River Basin has produced a significant sediment reduction effect. The multiple linear regression model effectively captures the variations in sediment load and demonstrates potential for application in other river basins within the Beibu Gulf region. Future attention should be given to ecological construction in urbanized areas. The results provide scientific support for sediment regulation, ecological restoration, and watershed management under the background of the Pinglu Canal construction.