The invention relates to the technical field of defoaming filling machines, in particular to a linear backflow defoaming filling machine. The linear backflow defoaming filling machine comprises a rack; the rack is provided with a conveying component; the rack is provided with an air cylinder bottle distribution components and bottle mouth clamping and positioning components in sequence along the conveying direction of the conveying component; backflow-type filling nozzles are arranged above the bottle mouth clamping and positioning components; and the backflow-type filling nozzles are fixed on the rack. After the structure of the linear backflow defoaming filling machine disclosed by the invention is adopted, when each bottle reaches a filling position, the corresponding filling nozzle presses down a bottle mouth under the drive of an air cylinder; a valve port of the filling nozzle is jacked open by the bottle mouth, and excess liquid after the bottle is filled up flow backs to a liquid storage pot through a liquid return port; the filled bottles are transferred to the next process flow through the bottle outlet end of the conveying belt; filling or retained filling of a high-position liquid storage pot is executed by adopting a sanitary centrifugal pump, and by matching with liquid supplement and backflow of a low-position liquid storage pot, cleaning and installation are convenient.