The present invention relates to a traffic collision warning device comprising: a main circuit board (11); a central processing unit (12) being mounted on the main circuit board (11) and controlling the operation of the device; a memory (111); a warning signal generator (18); sensors (c1, c2, c3, c4, c1′, c2′, c3′, c4′) being arranged along the road near a collision-prone area; a vehicle identification module; timers (tm, tm′); vehicle counters (n, n′); and a movement direction comparison module. Wherein, the direction of movement of a vehicle is identified based on the order in which it passes through the sensors, the vehicle velocity is calculated by dividing the distance between the two sensors by the period of time it takes the vehicle to pass through the two sensors; the vehicle length is calculated by multiply the vehicle velocity and the period of time it takes the vehicle to pass through a sensor. When at least two vehicles moving from opposite directions are possibly to meet each other in the collision-prone area, the device emits collision warning signals at different levels depending on the velocities of the vehicles.