采用弹性理论研究了圆柱形胶体在表面张力作用下的弹性失稳问题；利用能量泛函变分的方法导出 了发生弹性失稳的非经典边界条件，得到了失稳的判据方程。分析判据方程发现，弹性失稳与圆柱体的半径、 内禀尺度和失稳波长相关。

The elastic instability of a gel cylinder was researched with classical elastic theory. The non-classic boundary condition of the elastic instability has been educed by the energy functional variation analysis.  So a criterion equation of the elastic instability can be got. Through the analysis of the equation, it is found that the elastic instability is relevant to the radius, intrinsic scale and instable wavelength of the cylinder.