[Objective]This study aimed to explore the morphological characteristics and nutrient content of fine roots of 2-year-old and 3-year-old Eucalyptus grandis plantation and investigate the correlation.[Method] Fine roots of 2-year-old and 3-year-old Eucalyptus grandis plantation were collected as experimental materials,to determine the root diameter (D),root length (L),specific root length (SRL) and contents of major nutrient elements N,P,K,Ca,Mg and C of fine roots (level1-5),study the morphological characteristics and major nutrient element content and investigate the correlation.[Result] The results showed that morphological differences of fine roots (level1-5) of Eucalyptus grandis plantation were great with the increase of root order,to be specific,D and L increased and SRL decreased with the increasing root order;SRL,L and D of 3-year-old Eucalyptus grandis plantation were greater than those of 2-year-old Eucalyptus grandis plantation. Contents of N,Ca,Mg and C of fine roots of 2-year-old and 3-year-old Eucalyptus grandis plantation showed consistent orders with the increase of root order:N and Mg contents were reduced,while Ca and C contents were enhanced;P and K contents varied with different forest ages;both 2-year-old and 3-year-old Eucalyptus grandis showed an order of C > K > Ca ( Mg) > N. Major nutrient element content and morphological characteristics of Eucalyptus grandis fine roots (level1-5) were extremely significantly correlated (P < 0. 01),SRL,L and D could be adopted as reference indices to evaluate nutrient status of Eucalyptus grandis.Required nutrients and fine root morphology of Eucalyptus grandis plantation changed with the increase of forest age,and the nutrient cycling and energy flow patterns also changed; major nutrient elements in fine roots of 2-year-old and 3-year-old Eucalyptus grandis plantation transferred in a different order from the growth order,therefore N fertilizer could be applied to improve the growth of fine roots.[Conclusion]This study laid the foundation for understand
