The invention discloses a traffic overflow pre-coordination method based on a movable virtual signal. The method comprises the following steps: collecting road and signal timing data, arranging overflow detectors and virtual signal projection devices, detecting time and speed of traffic flow queuing waves of upstream and downstream road sections arriving at the detectors and predicating the maximum traffic flow queue length; judging whether the maximum traffic flow queue length reaches a threshold value of overflow queue length, and if predicating that an overflow state can be reached, judging traffic state of the upstream road section during detection of the overflow detector according to the collected signal timing data, and determining stop position of the virtual projection device; and calculating and adjusting go-ahead signal projection time of the virtual signal device to project the state of stop signals, and driving the virtual signal device to a stop line at a certain speed along a rail in the vehicle driving direction to enable traffic flow to follow the device to drive at the same speed. The newly-added pre-signals can effectively prevent occurrence of overflow under the premise of not influencing normal operation of main signals of an intersection.