摘 要 本文采用白光数字散斑相关方法对煤在单轴压缩下变形破坏进行研究，定量的测出了煤的变形局部化带宽度。并通过应变梯度塑性理论，在屈服函数中引入应变梯度二阶项。采用Drucker－Prager准则解析得出了煤试件的变形局部化带宽度公式并根据试验确定煤的材料内部长度。 Abstract In this paper, the white digital speckle correlation method is used to study the deformation and failure of coal under uniaxial compression. The deformation localization band of coal is quantitatively measured. And through the strain gradient plasticity theory, the strain gradient second order term is introduced into the yield function. Based on the Drucker-Prager criterion, the deformation localized band width formula of the coal specimen is obtained and the internal length of the coal material is determined according to the experiment.