In recent years,high voltage cross linked polyethylen (XLPE) cable buffer layer ablation defects occur frequently,which has a serious impact on the safe operation of the cable. It is extremely urgent to study how to reduce the impact of the buffer layer defects. Therefore,how to reduce the severity of the buffer layer ablation defects by improving the aluminum sheath structure is studied in this paper. Firstly,the reason of ablative defect of buffer layer is analyzed theoretically. Secondly,the buffer layer voltage calculation model is established. Finally,a defect cable is taken as the simulation object to calculate the suspension potential and the electric field intensity of the buffer layer after reducing the minimum inner diameter and the curvature at the trough of the aluminum sheath respectively with the white spot defect of the buffer layer. Taking the defective cable as an example,the simulation quantitative analysis shows that when the minimum inner diameter decreases,the suspension potential of insulation shielding decreases by 30%,and the electric field intensity between buffer layers decreases by 30.9%. When the curvature at the trough of the aluminum sheath decreases,the suspension potential of insulating shield decreases by 13.7%,and the electric field intensity between buffer layers decreases by 13.3%. When the buffer layer white spot appears,the decrease of the minimum inner diameter and the curvature at the trough of the aluminum sheath lead to the suspension potential of the insulating shield layer and the electric field intensity between the buffer layer decrease,thus reducing the possibility of partial discharge and the impact caused by the buffer layer defect.