A method and a device for calculating a minute ventilation of a medical breathing apparatus. The method comprises: recording breathing data in real time the data comprising time of each inspiration and an expiratory tidal volume of breathing prior to each inspiration (S102) and each time when breathing data is recorded calculating a minute ventilation of the medical breathing apparatus according to the data recorded in the current recording operation and in a preset time duration before the current recording operation (S104). The method can calculate the minute ventilation of a patient quickly and accurately thereby solving the problem of slow measurement of ventilation in unit time in the prior art.
