The flexural buckling of a spatial elastic thin rod under torque is discussed with FEM(finite element method).In a natural coordinate system,an energy equation is given,which considers nonlinear terms of the tortuosity about an initially curved and twisted thin rod with circular cross-section.An eigenvalue analysis is proposed to study the buckling of spatial elastic thin rods with simultaneous effect of axial force and torque.The method is clearly demonstrated by examples.Numerical results are in good agreement with theoretical solutions.