The invention relates to a flow mixing device with a triple flow mixing function. The flow mixing device with the triple flow mixing function comprises an air chamber located in a cooling tower, and the top of the air chamber communicates with an air cylinder of the cooling tower. The cooling tower is further internally provided with a dry cold area and a wet cold area which are located below theair chamber, and the bottom of the air chamber communicates with the dry cold area and the wet cold area in the cooling tower. The air chamber is internally divided into a first flow guiding area at the bottom, a second flow mixing area in the middle and a third flow mixing area on the upper portion. A plurality of first flow guiding devices are arranged in the first flow guiding area and arrangedabove the dry cold area. The third flow mixing area is arranged below the air cylinder and internally provided with a plurality of second flow guiding devices, and the multiple second flow guiding devices are circularly arranged at the bottom of the air cylinder. The flow mixing device has the characteristics that dry and wet air in the cooling tower can be fully mixed, and the fog-dispersal effect of the cooling tower is improved.