Shift control method in DCT vehicle

A shift control method in a vehicle having a dual clutch transmission, comprising:

• determining whether or not power-off downshifting is started and whether or not torque handover is started;
• determining whether or not the vehicle has entered a rough terrain, when the torque handover is started;
• determining and storing a speed change rate of an engaging input shaft before the vehicle enters the rough terrain when it is determined that the vehicle has entered the rough terrain;
• determining a target transfer torque of an engaging clutch based on the speed change rate of the engaging input shaft that is stored during determining and storing the speed change rate of the engaging input shaft when the vehicle has entered an actual shifting section, and increasing a transfer torque of the engaging clutch by an amount until arriving at the target transfer torque of the engaging clutch;
• controlling the target transfer torque of the engaging clutch to be maintained until a slip rate arrives at a reference value after determining the target transfer torque of the engaging clutch;
• and
• completing the power-off downshifting by reducing the transfer torque of the engaging clutch by the amount of torque that the engaging clutch was increased at the step of increasing the transfer torque of the engaging clutch when controlling the target transfer torque of the engaging clutch is completed.