The invention discloses a narrow-beam millimeter-wave human heartbeat/respiratory sign monitoring device with controllable irradiation direction. The device comprises a millimeter-wave radar, a millimeter-wave lens antenna, an AD acquisition card, an intelligent beam control mechanism and upper computer software, a specially-made narrow-beam low-sidelobe small-size millimeter wave antenna lens is additionally arranged at the front end of a radar receiving and transmitting antenna, so that the signal-to-noise ratio of a radar receiver is improved. The direction of a main beam of a radar device is changed through a beam control mechanism, and the maximum position of the monitored human body surface heartbeat amplitude is automatically searched for according to the amplitude characteristics obtained after phase demodulation of intermediate frequency signals of the radar receiver. The device reduces the influence of respiratory harmonics and clutters on heart rate discrimination, improves the heart rate measurement precision, is suitable for single-person or multi-person monitoring, achieves the precise measurement of respiratory and heartbeat frequencies under the condition of no contact with a human body, can recognize the abnormal physiological states of arrhythmia, respiratory failure and the like, improves the accuracy of heart rate measurement, has an application prospect in the aspect of clinical dynamic monitoring of critical patients with infectious diseases and burns, and is also used for vital sign monitoring in daily life.