Left deviation of the electrical axis needs to be clarified by electrocardiography. If the electrical axis is mildly deviated to the left, it usually does not matter. Severe left deviation of the electrical axis may indicate heart disease, which should be further examined and timely consultation should be made, otherwise it may lead to further development of the disease. Electrocardiography is a commonly used clinical examination method, widely popularized and applicable to most people. Normal ECG axis is -30°~+90°, when the axis is -30°~-90°, the axis is left deviation. Physiological causes can be seen in healthy short and fat people, and pathological causes can be seen in left ventricular hypertrophy and left anterior branch block, but the left deviation of the electrical axis suggested by the ECG is not a clear diagnosis, and further cardiac ultrasound and other examinations are needed. If the electrocardiogram indicates left deviation of the electrical axis and is accompanied by symptoms such as cardiac discomfort, it is recommended to consult a doctor in time for a clear diagnosis and symptomatic treatment.