根据弯曲梁理论，建立了套管柱受非均布外挤压力作用的力学模型；并应用解超静定问题的正则方程和力法准则对该力学模型进行求解，得到了在非均布外挤压力作用下套管圆周上的弯矩、剪力、轴力、应力和位移的分布规律。计算表明，在非均布外挤压力作用下，套管抗挤毁强度大大降低。该力学模型不仅可以解释深井套管挤毁机理，而且可以改进深井套管抗挤强度设计。 According to the bending beam theory, a mechanical model of casing string subjected to non-uniform external extrusion is established. The mechanical model is solved by using the normal equations and the force law criteria for solving the problem of over-statics. The Distribution Law of Bending Moment, Shearing Force, Axial Force, Stress and Displacement on Casing Pipe under External Extrusion. The calculation shows that under non-uniform external extrusion pressure, the collapse resistance of the casing is greatly reduced. The mechanical model can not only explain the deep casing collapse mechanism, but also improve the design of deep casing collapse strength.