Sudden cardiac death (SCD) is progressively threatening the lives of young people throughout the world. We conducted a retrospective study of SCD cases identified among sudden death cases based on comprehensive autopsies and pathological examinations in the Center for Medicolegal Expertise of Sun Yat-Sen University to investigate the exact etiological distribution and epidemiological features of SCD. One thousand six hundred fifty-six cases were identified, and SCD accounted for 43.0% of these sudden death cases. The mean age of the SCD cases—where the data of definite ages were accessible—was 38.2 years, and the highest incidence occurred among the 31- to 40-year-old cases (25.6%). The male-to-female ratio among SCD cases was 4.3:1, and this ratio peaked in the 41- to 50-year-old group (7.7:1). The places of death were confirmed in 1411 cases, and predominantly in hospitals (46.3%) and at home (33.8%). SCD occurred throughout the year with a marginally increase in April and May. The major causes of SCD were coronary atherosclerotic disease (CAD, 41.6%), unexplained sudden death (15.1%), and myocarditis (11.8%). Our data indicated that in the age group of younger affected persons (below 35 years old), sudden unexplained death and myocarditis were much more prevalent than CAD. According to anatomical examinations of the CAD-related SCD cases, the proportion of cases with coronary artery stenosis exceeding 75% (grade IV) was 67.2%. Moreover, the percentages of higher grades of coronary atherosclerosis increased with age. Among all branches of the coronary arteries, the left anterior descending branch was the most prone to atherosclerosis; atherosclerosis was present in this branch in 95.4% of the cases with atherosclerosis. Additionally, lesions of multiple branches of the coronary artery were associated with ageing. This is the first study to report the causes of death and basic epidemiological data related to SCD in Southern China.