【Objective】The objective of this study is to obtain fertilizing effects of interplanting forage legumes and corresponding handling modes, which would be lay a basis for fertilizing measures of young orchard in hilly red soil region of south Hunan.【Method】In order to explore effects of interplanting forage legumes and corresponding handling modes on soil fertility in young citrus orchards, a field experiment was carried out interplanting six species of forage legumes, including Trrifoliumrepens, Chamaecradtanictitans, Chamaecristarotundifolia, Chamaecristarotundifolia CPI 86134, Macroptiliumlathyroides, and Lotononisbainesiiwere, separately and designed to have the crops, harvested, laid over or plowed down, in a young citrus plantation in a hilly red soil region of South Hunan. Soil physicochemical properties of all the plots were measured after the experiment for analysis of the effects. 【Result】 Results show as follows. Compared with CK (no crop interplanted), all the plots, on the whole, increased in contents of organic matter, total nitrogen, alkali-hydrolyzable nitrogen, and available phosphorus, and the increasing effects were the highest in the plots with the crops plowed down or incorporated, but decreased in content of readily available potassium and pH, and the decreasing trends were the lowest in the plots with the crops plowed down. Among all the plots, the plot with Chamaecradtanictitans plowed down raised the contents of organic matter, total nitrogen, alkali-hydrolyzable nitrogen, and available phosphorus contents the highest in margin and lowered the content of readily available potassium the least, and the plot with Chamaecristarotundifolia incorporated came the next in the effects. Besides, the plot with Chamaecradtanictitans incorporated lowered soil pH the least. Compared with CK, all the plots increased fruit yield, single fruit weight, and tree height, canopy diameter, and number and length of spring/autumn branches of the orange trees. The effect of the plot with Chamaecradtanictitans incorporated was the most significant and the plot with Chamaecristarotundifolia incorporated came the next. Besides, the plot with Chamaecradtanictitans incorporated was the highest in biomass of the forage legume yielded, and in amount of nitrogen and phosphorus returned into the soil, and in soil microbial biomass carbon, soil microbial biomass nitrogen, and urease activity, too. 【Conclusion】Therefore, it can be concluded that the practice of interplanting Chamaecradtanictitans and then incorporating the crop is the most suitable soil building mode for young citrus orchards, but it needs supplementation of some potassium and phosphorus fertilizers. Besides, it is also necessary to apply some alkaline material, like lime, to offset the effect of interplanting forage legumes lowering soil pH.