A medical ventilation system, comprising: an input device, a first gas source interface, a second gas source interface, a respiratory line, a drive gas branch, a fresh gas branch, and a ventilation controller; wherein one end of the drive gas branch is connected with the first gas source interface, and the other end of the drive gas branch is connected with the respiratory line; one end of the fresh gas branch is connected with the first gas source interface and the second gas source interface, and the other end of the fresh gas branch is connected with the respiratory line; the ventilation controller is configured to control the drive gas branch to provide ventilation support for a patient through the respiratory line, and to control the fresh gas branch to output a fresh gas which contains anesthetic drug to the respiratory line, according to first mode control information which is received by the input device; characterized in that, the ventilation controller is further configured to control the drive gas branch to output, a gas which is outputted by the first gas source interface, to the respiratory line; and to control the fresh gas branch to output, at least a gas which is outputted by the first gas source interface or the second gas source interface, to the respiratory line; according to second mode control information which is received by the input device; the ventilation controller is further configured to, according to the second mode control information, control the fresh gas branch to output the gas by turning off an anesthetic evaporator or providing an evaporator bypass in the fresh gas branch. an input device, a first gas source interface, a second gas source interface, a respiratory line, a drive gas branch, a fresh gas branch, and a ventilation controller; wherein one end of the drive gas branch is connected with the first gas source interface, and the other end of the drive gas branch is connected with the respiratory line; one end of the fresh gas branch is connected with the first gas source interface and the second gas source interface, and the other end of the fresh gas branch is connected with the respiratory line; the ventilation controller is configured to control the drive gas branch to provide ventilation support for a patient through the respiratory line, and to control the fresh gas branch to output a fresh gas which contains anesthetic drug to the respiratory line, according to first mode control information which is received by the input device; characterized in that, the ventilation controller is further configured to control the drive gas branch to output, a gas which is outputted by the first gas source interface, to the respiratory line; and to control the fresh gas branch to output, at least a gas which is outputted by the first gas source interface or the second gas source interface, to the respiratory line; according to second mode control information which is received by the input device; the ventilation controller is further configured to, according to the second mode control information, control the fresh gas branch to output the gas by turning off an anesthetic evaporator or providing an evaporator bypass in the fresh gas branch.