In order to explore the evolution of soil and water conservation benefits of vegetation at different growth stages during the implementation of grass planting measures on granite red soil erosion and degraded slopes, this study set up three different grass planting patterns, including strip type (D1), random type (D2), patch type (D3), and an eroded degraded bare slope (CK) as the control to conduct experiments. The characteristics of slope soil erosion during the whole vegetation growth process were monitored under natural rainfall conditions. The results showed that:(1) The growth of vegetation could significantly improve the soil and water conservation ability of slope. With the advancement of vegetation growth stage, the runoff and sediment yield of slope decreased obviously.The runoff reduction benefit could reach from 20.74% to 79.03%, and sediment reduction benefit could reach from 97.42% to 99.40%. Under different rainfall types, with the growth of vegetation, the increasing and changing laws of the benefits of runoff and sediment reduction on the slope were different. (2) Vegetation growth could gradually weaken the influence of rainfall factors on slope sediment yield, so that the difference in slope sediment reduction rate between different rainfall patterns gradually decreased, and sediment reduction finally stabilized at a high level. The difference of runoff reduction rate on the slope between different rain types was large in each vegetation growth period. There was a logarithmic function relationship between runoff reduction rate, sediment reduction rate and vegetation growth time, with correlation coefficients greater than 0.491 and 0.792, respectively. Vegetation growth indicators (tiller number, coverage, plant height) were significantly or extremely significantly negatively correlated with the runoff and sediment yield of slope. (3) From the perspective of the entire vegetation growth process, the order of 3 grass planting pattern for soil and water conservation benefits was D1>D3>D2. In the early stage of vegetation growth, the distribution pattern of high plant density was stronger than that of low plant density, and the difference of each pattern was small in the later stage. The results provide scientific basis and technical support for vegetation restoration in seriously eroded degraded areas of the red soil region of south China.