<p>In order to study the deformation and cracking behavior of casing with defects under non-uniform load, different types of defects were prefabricated on the surface of casing samples by building a test system. The cracking and crack propagation process of samples under non-uniform load were observed and analyzed by finite element simulation. The test results show that the defect will significantly reduce the bearing capacity of the casing under non-uniform load, and the defect is a necessary condition for the cracking failure of the material. The defect depth affects the bearing capacity of the sample, and the defect width affects the deformation of the sample. With the increase of the depth of the defect, the maximum load of the sample and the maximum load loading displacement approximate S curve decrease; with the increase of the width of the defect, the deformation of the sample under the same load in the load reduction stage of the sample increases obviously. The variation curve of crack length with loading displacement is obtained, and the finite element model of casing with defects is established, which can analyze and evaluate the stress and deformation distribution of casing. The research results can provide guidance for casing damage evaluation and field detection.</p>