A method and system for assisting driver are provided in the present disclosure, in which images captured by a single image sensing device is processed by a controller having capability of image processing and identification and distance estimation in image space for providing a complete assisting image-information while the carrier is moving forward or backward. By means of the method and system of the presented disclosure, it can identify the image characteristic to be a basis for lane departure assistance/alarm while the carrier is moving forwardly as well as generate assisting track and change view angle or issue an alarm according to the distance estimation while the carrier is moving backwardly. The present disclosure may be utilized and applied in different kinds of carrier type to solve the problem of guiding of carrier maneuvering, and assist carrier lane changing, parking assistance and blind spot detection.