A Lane-keeping control method and system of a vehicle include an estimated control entry boundary arrival time setting controller for setting an estimated control entry boundary arrival time to arrive at a control entry boundary and a look-ahead distance calculator for calculating a look-ahead distance on the basis of the estimated control entry boundary arrival time and vehicle velocity. A lane-keeping control entry determiner determines whether to enter the lane-keeping control on the basis of the control entry boundary, a lane-keeping control torque producer produces a lane-keeping control torque in a direction opposite to a lane-departure direction whether to enter lane-keeping control, and a torque releasing controller releases the lane-keeping control torque when the vehicle has returned to the inside of a control release boundary after the lane-keeping control torque was produced.