【Objective】Vegetation and topography are two important factors determining runoff and sediment yielding in slope soil erosion process. Studies reported in the past were mostly focused on effects of single control factors, e.g., slope gradient or vegetation cover, on runoff and sediment yielding, and few were found in the literature on coupling effects of vegetation and topography on runoff and sediment yielding and converging process. The Yellow River Basin in China is one of the most severely eroded regions in the world, and the lower reaches of the River is world-famous for its silt-carrying load. Under the impact of a long history of human activities, its riparian zones have been suffering serious soil erosion. However, little has been reported quantitatively on soil erosion in the riparian zones of the River. What is more, restoration and preservation of the ecological functions of the riparian zones are closely related to the interactive effects of vegetation and topography on soil erosion and hydrological connectivity on the riparian slopes. 【Method】In this study, a field experiment simulating rainfall on riparian slopes along the lower reaches of the Yellow River to investigate runoff and sediment yielding characteristics as affected by rainfall intensity (54 and 90 mm h^-1), slope gradient (5°, 10°, 15°, and 20°), and vegetation coverage (0%, 15%, and 30%), as well as effects of slope gradient and vegetation coverage on soil erosion and relationships of runoff and sediment yielding characteristics with flowlength with the aid of a hydrological connectivity model. 【Result】Results show that vegetation cover, regardless coverage, helped reduce runoff velocity under rainfall, no matter how heavy, either 54 or 90 mm h^-1 in rainfall intensity, and the effect was the most significant on a slope 30% in vegetation coverage under artificial rainfall, 90 mm h^-1 in intensity. Runoff on slopes varied in volume and depth consistently, gradually declining with rising slope gradient and vegetation coverage, and the effect of slope gradient increased gradually with intensifying rainfall. On slopes, < 15°, erosion sediment yield under rainfall 54 mm h^-1 in intensity increased slowly with rising slope gradient, however, the effect of slope gradient was not very obvious, whereas on slopes > 15°, the increment became bigger in magnitude. On slopes, < 15°, erosion sediment yield under rainfall 90 mm h ^-1 in intensity, erosion sediment yield increased with rising slope gradient, whereas on slopes > 15°, it went reversely. Correlation analysis shows that slope gradient was the major factor affecting sediment yield, runoff volume and runoff depth at a significance level of p<0.001, p<0.01 and p<0.01, respectively, while vegetation coverage had a significant effect only on average runoff velocity (p<0.05), but an extra-significant one on flowlength (p<0.001). Runoff had a much longer flowlength on bare slopes than on vegetated slopes, while flowlength on vegetated slopes did not vary much with vegetation coverage. Vegetation cover on slopes was the main reason for difference in hydrological connectivity between slopes. In exploration of hydrological connectivity and runoff-sediment yielding, it was found that they were closely correlated, and runoff and sediment yielding exhibited a rising trend with increasing flowlength. 【Conclusion】Under the interaction of vegetation cover and slope gradient, soil erosion caused by runoff yielding was obviously affected by slope gradient, but not as much as by vegetation coverage. All the findings in this study may serve as references for assessment of soil and water conservation functions of and ecological restoration of degraded riparian zones along the lower reaches of the Yellow River.