The utility model relates to a pneumatic conveying accessory, in particular to a pneumatic conveying air supplement device. According to the pneumatic conveying air supplement device, guiding bodies used for guiding air supplement flows are arranged on the outer wall of a conveying pipe, and the guiding bodies are used for guiding supplemented air flows so that supplemented air flows can be evenly mixed with air flows in the conveying pipe. In the work process of a system, supplemented air flows through the air supplement device are guided through the guiding bodies, the structure is simple, the guiding bodies can normally work basically without maintenance in the work process of the system, air holes do not exist in work of the air supplement device, the blocking problem is avoided, and the air supplement device has a good air supplement effect and is simple in structure and convenient to maintain.