Abstract: To study the influences of initial residual stress of blanks and cutting stress in the machining process on deformation of thin-walled parts, according to residual stress test by hole-drilling method for casting aluminum alloy tapered thin-walled blank, three finite element models were established. By comparing three models, the results show that initial residual stress and cutting stress have a significant effect on workpiece deformation after processing. Among them, cutting stress has the most significant influence.