A respiration detection device includes a mouth guard mounted in a mouth of a user. A coupling seat is mounted to a front end of the mouth guard and is located in a position in front of a nose and the mouth of the user. A detection unit includes a circuit board, a microphone, a micro-processing circuit, and a transmission circuit. The circuit board is mounted to the coupling seat and is connected to a battery. The micro-processing circuit, the transmission circuit, and the microphone are mounted on the circuit board. The micro-processing circuit is configured to receive and process a message from the microphone to indicate a respiratory rate of the user. The transmission circuit is electrically connected to the micro-processing circuit and is configured to proceed with data transmission with an external device. The respiration detection device can accurately detect the respiratory rate in real time.
