By the variational principle, this paper derivesthe equilibrium equation and the boundary condition of thelarge-deflection flexible bar, which improves the results inreferences [2] and [3].

• 利用变分原理；不仅给出了柔杆在大变形时的平衡方程；同时也给出相应的边界条件；弥补了文献[2]和文献[3]在这方面的缺陷.