In order to understand directionality of turning residual stress distribution, 45 steel by thermal refining and quenched was turned in fine/rough machining conditions. Then circumferential distribution characteristics of residual stress in different samples were observed, and influence of mechanical properties of materials and cutting conditions on directionality of residual stress was understood. Results show that residual stress distribution is directional, maximum of residual stress is on axial direction and minimum is on radial direction;directionality of residual stress is mainly determined by mechanical effect, and thermal effect is not obvious;magnitude and change rate of residual stress in different directions are affected by mechanical properties of workpiece materials and processing conditions;the greatest impact is axial residual stress on turning workpiece than other direction.