Disclosed is an airflow balance device suitable for blowing-carding cotton road transportation. The airflow balance device is characterized by comprising a card transportation channel, a cotton road observation window, a return air diffusion box, a return air box adjusting plate, a return air pipe and an airflow separation and combination part; a cotton outlet is arranged in the left end of the cotton transportation channel, a cotton inlet is arranged in the right end of the cotton transportation channel, the cotton road observation window is located in the front side of the cotton transportation channel, the return air diffusion box is located at the rear side of the cotton transportation channel and is communicated with the same, the return air box adjusting plate and the air return pipe are sequentially arranged at the top of the return air diffusion box, and the airflow separation and combination part is arranged between the return air diffusion box and the cotton transportation channel; the airflow separation and combination part is commonly formed by filter screens clamped between a box combining part and a mesh plate combing part.