In order to meet the requirements of numerical control system to control feeds peed in highspeed and highaccuracy machining, the conditions of direct trans iting under the adjacent path segments are determined, and the correcting proble m of turning speed is researched according to the transiting angle when the condi tions are not feasible. The dealing principle of acceleration/deceleration in on e segment is presented and the feedspeed is replaned under the basis of invar iableness length. The trouble of forecasting deceleration point and end point us ing the past methods is avoided. The result of practical computation indicates t h at the proposed method, relative to the method of turning speed ‘0’, enhances the machining efficiency(about 2% per segment) based on assuring accuracy and c ould be well applied to highspeed machining system.