A method and a device for calculating a breathing frequency of a medical breathing device. The method comprises: recording breathing data in real time the data comprising the time of each inspiration and an inspiration state and the inspiration state comprising with inspiration and without inspiration(S102) and each time the breathing data is recorded calculating the breathing frequency of the medical breathing device according to data recorded in the current recording operation and data recorded within a preset period of time prior to the current recording operation (S104). Through the method and the device the problem of slow calculation of the breathing frequency can be solved and the breathing frequency of a patient can be calculated within a time as short as possible.
