Abstract: Analyzed in the paper are the relevant data of casing damages occurred in domestic shale gas exploiting operations as well as the exsisting shale gas well conditions to find out the fundamental causes for point deformations appeared on casings.The analysis indicates that when the external non-uniform load borne by a casing body exceeds its limit,it will lead to overall structure instability of the casing and cause point deformation.The bearable non-uniform load for a casing is calculated by finite element method and verified by actual product evaluation test to provide a precise theoretical basis for the type selection of casings for shale gas well.Some solutions for reducing casing damages in shale gas wells are put forward.