The invention relates to a pipe cleaning ball circulation device and a work method thereof. The circulation device comprises a rack, a liquid box, a fluid pump and a ball serving mechanism. A ball-liquid separation groove is formed in the outlet end of a to-be-cleaned pipe and comprises a side plate and a filter plate with the oblique bottom, a ball outlet is formed in one end of the filter plate,and the ball outlet is guided to a ball adding port of the ball serving mechanism. The liquid box for recycling fluid filtered and separated through the filter plate is arranged at the bottom of thefilter plate. According to the work method, after cleaning balls are served through the ball serving mechanism, the cleaning liquid cleans the to-be-cleaned pipe, the cleaning balls and the cleaning liquid obtained after cleaning fall into the ball-liquid separation groove, through separation of the cleaning balls and the cleaning liquid, the separated cleaning balls fall into the ball serving port of the ball serving mechanism again along with the dead load, the cleaning liquid is recycled into the cleaning liquid box, and accordingly pipe cleaning ball circulation is achieved. According to the pipe cleaning ball circulation device and the work method thereof, automatic cleaning ball circulation is achieved, the operation of manual ball collecting and moving is omitted, and the pipe cleaning efficiency is improved.