A lane keeping assist method and system may include determining a driving state of a vehicle according to a state of a lane change in which an intention of a driver is reflected after a turn signal is applied, adjusting a criterion for driver override depending on an error between a driving path of the vehicle and a target path according to the driving state of the vehicle, comparing a steering torque of the driver with the adjusted criterion to determine activation or cancellation of the driver override, minimizing the driver's discomfort in the steering operation when the driver intentionally changes the lane.