The invention discloses a sudden death early-warning method, device and system. The method comprises the steps of 1, extracting and detecting physiological information, wherein respiration, oxyhemoglobin saturation, heart rate and heart rate variability information of a testee are extracted, and totally the 6 monitoring indexes of the respiratory rate, the AHI index, the arterial oxygen saturation, the heart rate, the Poincare map indexes SDI and SD2 are obtained; 2, detecting abnormity of the physiological information, wherein various kinds of physiological information obtained in step 1 aresubjected to abnormity detection and early-warning level calculation; when abnormity is detected, step 3 is executed if the result shows abnormity, and detection continues if the result shows normality; 3, conducting sound, light and vibration alarming, wherein an alarm apparatus is driven to give out sound, light and vibration, and the corresponding early-warning level is offered; it shows that the higher the early-warning level is, the higher the risk of sudden death is, and when the early-warning level is larger than 3, the testee needs to see a doctor, and if the early-warning level is larger than 5, the testee needs to see a doctor urgently. The sudden death early-warning device comprises a respiratory sensor module, an oxyhemoglobin saturation sensor module, a heart rate sensor module and a microprocessor module.