Abstract: The present disclosure relates to a device for liquid processing in the process of cell culture, comprises: a settling tank which is configured to store a cell culture fluid from a bioreactor; a communicating tube that allows the bioreactor to communicate with the settling tank; a first excretory tube for discharging a cell concentrate, which is connected to the settling tank; a second excretory tube for discharging a supernatant, which is connected to the settling tank; a pump; and a control unit. In such device, after the cell culture fluid is separated into the supernatant and the cell concentrate by the gravitational settling in the settling tank, the control unit is configured to control the pump to (a) return the supernatant to the bioreactor through the communicating tube and harvest the cell concentrate through the first excretory tube and/or (b) harvest the supernatant through the second excretory tube and return the cell concentrate to the bioreactor through the communicating tube.