Objective To explore the correlation between hypokalemia and sudden death in young and middle-aged people. Methods One hundred and twenty-nine young and middle-aged patients with sudden death during treatment were selected as observation group. Then 100 cases of healthy volunteers were randomly selected as control group. The incidence of cardiovascular disease, incidence of hypokalemia and intake of potassium were compared between 2 groups. Results The incidences of hypertension, arrhythmia, myocardial infarction, heart failure and hypokalemia in observation group were significantly higher than those in control group: 17.05% (22/129) vs. 5.00%(5/100), 13.18% (17/129) vs. 2.00% (2/100), 26.36% (34/129) vs. 9.00% (9/100), 9.30% (12/129) vs. 1.00% (1/100) and 55.04% (71/129) vs. 12.00% (12/100), and there were statistical differences (P<0.01). The ratios of higher, common, lower intake of potassium in observation group were 1.55%(2/129), 27.91% (36/129) and 70.54%(91/129), in control group were 15.00% (15/100), 58.00% (58/100) and 27.00% (27/100), and there was statistical difference (P<0.01). Logistic regression analysis result showed that hypertension, arrhythmia, myocardial infarction, heart failure, hypokalemia and lower intake of potassium were the risk factor for sudden death (P<0.01). The incidences of hypertension, arrhythmia, myocardial infarction and heart failure in hypokalemia patients were significantly higher than those in normokalemia patients: 28.92% (24/83) vs. 2.05% (3/146), 19.28% (16/83) vs. 2.05% (3/146), 44.58%(37/83) vs. 4.11% (6/146) and 13.25% (11/83) vs. 1.37% (2/146), and there were statistical differences (P<0.01). The incidence of hypokalemia in people with lower intake of potassium was significantly higher than that in people with higher and common intake of potassium: 56.78% (67/118) vs. 2/17 and 14.89%(14/94), and there was statistical difference (P<0.01). Conclusions There is a significant correlation between hypokalemia and sudden death in young and middle-aged people. Preventive measures of sudden death should be made according to serum potassium level in clinic. People should pay attention to the uptake of potassium in daily life.