The present invention relates to a pneumatic conveying system and a circulating fluidized bed (CFB) boiler, belonging to the technical field of CFB boilers. The system comprises an air compressor that supplies compressed air to an air-powder mixer, a coal powder bin that stores coal powder and feeds it into the air-powder mixer via a powder feeder, and the air-powder mixer, which blends the compressed air and coal powder to output an air-powder mixture. The outlet of the air-powder mixer is connected to a main conveying pipe, which branches via a distributor to multiple conveying pipes. These conveying pipes are connected to secondary air pipes on the front, rear, and side walls of the CFB boiler in a sleeve-type manner, delivering the air-powder mixture into the furnace chamber. The invention enhances the load change rate of CFB units from the current 1% Pe/min to over 3% Pe/min, reduces the ignition restart temperature, extends the ignition hold time, and ensures safe and rapid load increase for CFB units.