A 9-year observation was conducted at the experimental plots in the Citrus reticulata plantation in Jiangxi Provincial Eco-Technology Park to study the eco-hydrological characteristics and soil conservation benefits of the plantation on slope red soil. Seven treatments were designed and monitored over nine years. The average flow and the rate of sediment for the seven treatments were reduced by 78.5% and 77.2%, respectively. The reduction rates were the highest in treatments band coverage of Paspalum natatu, whole coverage of P. natatu, and level terrace with grass on ridge, with the values of 94.8%, 94.3% and 92.5%, respectively, followed by in treatment intercropping Glycine max (66.0%) and Raphanus sativus (77.5%), with horizontal planting being better than vertical planting, and the lowest in treatment without understory vegetation (33.1%). The observations on the precipitation redistribution of 43 rainfall events with a mean precipitation of 20.07 mm in 2009-2010 showed that the throughfall, stemflow, and canopy interception were 9.15, 4.72 and 6.20 mm, accounting for 44.7%, 25.7% and 29.6% of the precipitation, respectively. The throughfall and stemflow tended to increase with increasing precipitation. There was a significant liner negative correlation between the canopy interception rate and the precipitation when the rainfall was less than 10 mm, but no significant correlation when the rainfall was greater than 10 mm. The water holding rate of C. reticulata litters was logarithmically correlated with water soaking time, and the maximum water holding rate was 326%. It was considered that rational allocation of understory vegetation played an important role in the soil and water conservation of citrus orchard on slope red soil.