During the oil field development, casing damage is one of the major trouble. Because there is casing damage in the oil shale layer of many wells. It is particularly important for us to study the mechanisms and influencing factors about the casing damage of this layer. By conducting the study of oil shale lithology and the direction of geostress,determining the position by applying the interpretation results of well logging, we pointed out the relationship between casing damage and geostress and expounded the mechanism of the casing damage in oil shale layer. The research result provides the theoretical reference for controling and prevention the casings from damaging in oil shale layer.