In consideration of the impact of reservoir pressure change on overlyingmudstone, finite difference method is applied to carry out the simulation study of mudstone creep on the top of SⅠ mudstone in anticline structure in northern Lamadian Oilfield. The result shows that the maximumhorizontal principal stress is of - 25.87～- 24.88MPa in a direction of near EW, while the minimum principal stress is of - 19.95～- 18.44 MPa in a direction of near SN. The change of strain and displacement mainly displays in vertical direction. The more near the oil layer, the greater the strain and displacement are impacted by reservoir pressure change. The maximum displacement （or variable） of mudstone creep all occurred on the contact interface with the oil layer. The study of maximum strain of mudstone creep is favorable for preventing and controlling casing damage in oilfield.