Abstract:By inspecting and analyzing on vertical,horizontal distribution and competition of roots in Citrus intercropping wheat and planting Fagopyrum Mill as hedgerows,Citrus intercropping wheat and planting Camellia sinensis CL O.kuntze as hedgerows,Citrus intercropping wheat and planting Leucaena glauca as hedgerows etc agro-forestry systems,and fractional structure discipline of Citrus and Leucaena glauca,this research displays that root vertical and horizontal distribution curves obey typical Gauss curve and Lorentz curve;in comparison with Citrus intercropping wheat and planting Fagopyrum Mill as hedgerows,roots in agro-forestry system of Citrus intercropping wheat and planting Camellia sinensis CL O.kuntze as hedgerows have stronger competitive relation,reduction of output of wheat reaches 18.5 percent,average weight of Citrus decreases 14.3 percent;some fractional parameters of Citrus and Leucaena glauca have relation with 3/4 square of age of forest or L_(n-1).Studying on fractional branching principle will enrich optimizing methods on structure of agro-forestry systems,enhances its scientificness,maneuverability and foreseeable capacity.