The invention relates to a circular cutting machine for foaming cotton, comprising a building frame, an upper transmitting line, a lower transmitting line, a guiding ring, a shearing machine, a clamping cotton guiding device, a cutting machine, a material receiving device and a control system, wherein the upper transmitting line and the lower transmitting line are arranged on the building frame and are used for transmitting foaming cotton strips; the guiding ring is used for guiding the foaming cotton strips; the shearing machine is arranged on the building frame and is used for shearing the end surfaces of the foaming cotton strips horizontally; the clamping cotton guiding device is arranged on the side of the shearing machine and is used for positioning the foaming cotton strips; the cutting machine is arranged on the side of the clamping cotton guiding device and is used for cutting the foaming cotton strips; the material receiving device is arranged on the side of the cutting machine and is used for receiving rolls; the control system is used for controlling the work of the circular cutting machine for foaming cotton; the building frame comprises a fixing building frame and a movable building frame; the distance of the movable building frame can be changed relative to the fixing building frame and the shearing machine, the clamping cotton guiding device, the cutting machine and the material receiving device are orderly arranged on the building frame. The circular cutting machine for foaming cotton has the advantages of high working efficiency, low labor strength and low production cost.