Warning system for detecting approaching vehicle and method thereof

A warning method for detecting an approaching vehicle, comprising following steps:

• detecting a relative distance with respect to the approaching vehicle in a detection area to acquire a time to collision and detecting a driving path of the approaching vehicle with a detection unit, transforming the time to collision and the driving path into a detection signal, and outputting the detection signal;
• storing a warning information with a storage unit, the warning information including a predetermined time to collision, a warning area set in the detection area, and a confirmation condition for confirming that the approaching vehicle continuously moves in the warning area;
• and
• receiving the detection signal with a processing unit which is electrically connected with the detection unit and the storage unit to acquire the current time to collision and the current driving path of the approaching vehicle, such that when the time to collision is equal to or shorter than the predetermined time to collision, and the driving path falls in the warning area, and the driving path fulfills the confirmation condition, the processing unit sends a warning signal.