The invention discloses a method and a system for performing real-time cardiac monitoring by using a wearable electrocardiogram device. The method comprises the following steps: obtaining electrocardiogram data through a wearable device system, performing noise filtering, and obtaining a baseline shift-removed electrocardiogram; extracting the characteristics according to the baseline shift-removed electrocardiogram, and performing normalized classification to obtain a characteristic category; analyzing the obtained characteristic category, and taking corresponding measures according to the waveform generation situation. By implementing the embodiment of the invention, the cardiac health situation of patients whose cardiac health conditions are difficult to know and who are difficult to rescue in emergency situations can be easily monitored by a simple operation method; by using a mobile APP, two levels of danger warnings are established, the first level of danger warning helps the patients learn of cardiac discomfort and the second level of danger warning alerts emergency contacts that the patients are in an unexpectedly dangerous condition.