Splenic angiosarcoma (SA) is a rare disease that can cause spontaneous splenic rupture leading to unexpected death. The rare incidence and non-specific clinical presentations made the early correct diagnosis of SA impossible in clinical practice. Even with medical intervention, 80% of patients died within 6 months after diagnosis. Here, we report a man who had complained of abdominal distension for 2 weeks and succumbed to the disease nine hours after admission. Diagnosis of hepatic and splenic angiosarcomas was based on post-mortem histopathological examination and immunohistochemistry, and the cause of death was hemorrhagic shock caused by spontaneous splenic rupture secondary to SA. This present case was the first forensic autopsy of spontaneous splenic rupture secondary to SA, which can highlight the diagnosis of rare diseases in forensic practice, and forensic pathologists should bear in mind these rare diseases even in routine practice.