A movable carrier auxiliary system includes an environment detecting device, a state detecting device, and a control device. The environment detecting device includes at least one image capturing module and an operation module. The image capturing module captures an environment image in a traveling direction of the movable carrier. The operation module detects whether there is at least one of a target carrier and a lane marking in the environment image captured in the traveling direction for generating a detection signal. The state detecting device detects a moving state of the movable carrier and generating a state signal. The control device continuously receives the detection signal and the state signal, and controls the movable carrier to follow the target carrier or the lane marking according to the detection signal and the state signal upon receiving the detection signal that there is the target carrier or the lane marking in the environment image.