The utility model relates to a gas-solid separation device of a garbage pneumatic transmission system, which comprises a separator cylinder part, a separator taper cylinder part, an air inlet, an air outlet, a rotary cage and a pneumatic valve, wherein the air inlet is formed in the middle of the separator cylinder part; the air outlet is formed in the top of the separator cylinder part; the separator taper cylinder part is connected to a part under the separator cylinder part; the rotary cage is arranged at the air outlet; and the pneumatic valve is arranged at the bottom of the separator taper cylinder part. On the basis of a common cyclone separator, the rotary cage, in stead of a filter screen, is arranged at the air outlet, and under the action of high-speed airflow in the air outlet, the rotary cage is driven to quickly rotate by the movement of the airflow in the air outlet and the cyclone separator to take the effect of intercepting garbage to be separated from the air flow; and the rotary cage rotates at a high speed due to a large gap, has low possibility of blocking, and does not need to be cleaned basically. As external power is not required, the blocking and cleaning problems are solved.