An air cooling dry type slag conveying system of a coal-fired boiler comprises a machine shell, a large slag extrusion device installed above the tail portion of the machine shell, a slag bucket located above the large slag extrusion device and installed on the machine shell, an ash slag material conveying belt located below the large slag extrusion device and installed on the machine shell, a primary air pipe which is located between an entry strip ash slag material conveying belt and a return strip ash slag material conveying belt, installed on the machine shell and provided with a plurality of small air ports, an ash stopping plate installed on the small air ports of the primary air pipe, a slag smashing machine installed below the head of the machine shell, an automatic flow regulating valve installed in an air inlet in the head of the machine shell, and a flow meter installed on an air port below the automatic flow regulating valve. The air cooling dry type slag conveying system of the coal-fired boiler is good in cooling effect, rapidly raises air temperature, controls air volume accurately, enables the heat efficiency of the boiler to be high, saves energy, protects the environment, is high in conveying efficiency, is long in service life, and can be widely applied to the slag conveying process of the coal-fired boiler.