Second-degree sinus block refers to second-degree sinus conduction block, which is usually not serious if the patient is asymptomatic, and more serious if the patient has obvious symptoms, even symptoms such as blackness before the eyes, dizziness, and loss of consciousness, which are not treated in time. Second-degree sinus atrial block is a process in which there is a block or delay in the conduction of impulses from the sinus node to the atria. Determining the severity of second-degree sinus atrial block is a case-by-case process and cannot be generalized, as there is significant individual variability. Typically, in patients with second-degree sinus block who have no clinical symptoms, it is usually not serious and requires regular follow-up. However, if patients with second-degree sinus atrial block develop obvious clinical symptoms such as dizziness, weakness, blackness before the eyes, palpitations, syncope, etc., or if the treatment is not timely, it is relatively serious, and to a certain extent, it increases the chances of the occurrence of A. S. Syndrome. In summary, when the examination of second-degree sinus block, the patient needs to improve the poor lifestyle, on-time follow-up, if necessary, then need to actively cooperate with the doctor for standardized treatment.