A bioreactor applied to a bioartificial liver treatment system, comprising: a cover (6, 7), a container body, a sealing portion, a driving portion and a liquid guide portion, the liquid guide portion having at least a liquid inlet portion and the liquid outlet portion; wherein the cover body is detachably and fixedly connected to the container body, and the cover body is provided with a ventilation structure and a bacteria-retaining sealing breathable structure for making the internal and external air pressure of the bioreactor consistent; the liquid inlet is configured to deliver the liquid to be replaced into the container body; the liquid outlet portion penetrates the sidewall and the bottom of the container body to discharge the replacement liquid or the cleaned liquid out of the bioreactor; a gas-liquid channel is opened at the bottom of the container body;and the sealing portion is arranged along the outer sidewall of the bioreactor, and characterized in that the liquid inlet penetrates the sidewall of the container body, the bioreactor further comprises a cleaning liquid inlet portion including a cleaning liquid inlet pipe that penetrates the bottom of the driving portion to communicate with the inside of the driving portion, so as to deliver cleaning liquid into the driving portion; the driving portion is used to drive the replacement liquid or the cleaning liquid to move up and down through elastic deformation; and the sealing portion is used for fixedly connecting the container body and the driving portion to prevent the liquid from flowing out of the sidewall of the bioreactor, and wherein the cleaning liquid is physiological saline and the liquid to be replaced or the replacement liquid is plasma. a cover (6, 7), a container body, a sealing portion, a driving portion and a liquid guide portion, the liquid guide portion having at least a liquid inlet portion and the liquid outlet portion; wherein the cover body is detachably and fixedly connected to the container body, and the cover body is provided with a ventilation structure and a bacteria-retaining sealing breathable structure for making the internal and external air pressure of the bioreactor consistent; the liquid inlet is configured to deliver the liquid to be replaced into the container body; the liquid outlet portion penetrates the sidewall and the bottom of the container body to discharge the replacement liquid or the cleaned liquid out of the bioreactor; a gas-liquid channel is opened at the bottom of the container body;and the sealing portion is arranged along the outer sidewall of the bioreactor, and characterized in that the liquid inlet penetrates the sidewall of the container body, the bioreactor further comprises a cleaning liquid inlet portion including a cleaning liquid inlet pipe that penetrates the bottom of the driving portion to communicate with the inside of the driving portion, so as to deliver cleaning liquid into the driving portion; the driving portion is used to drive the replacement liquid or the cleaning liquid to move up and down through elastic deformation; and the sealing portion is used for fixedly connecting the container body and the driving portion to prevent the liquid from flowing out of the sidewall of the bioreactor, and wherein the cleaning liquid is physiological saline and the liquid to be replaced or the replacement liquid is plasma.