Abstract: Casing bend caused by sand inflow on the producing layer is a major problem in oilfield exploration.To solve the problem,this paper establishes a mechanical model of casing bend to explain the relative slipping and casing bend mechanism for some layer segments.Based on the mechanism of casing damage in the sand inflow layer,it takes the factors from geometry,physics and statics into account,analyzes some casing damage cases in the oilfield to deduce the mechanical model of casing bend and damage.The model has been validated by the practice data of a well in North China,which confirms that compacting and sand problems both result in casing bend.Good simulation effect has been achieved as well.Research results indicate that casing bend not only makes effective cross section decrease but also leads to casing snapping owing to larger local tensile stress.So effectively preventing sand and optimizing casing design is helpful to increase the overall economic results of oilfield production.