Primary cardiac angiosarcomas are rare tumors. Here, we report a case of primary cardiac angiosarcoma originating in the left atrium. The tumor resulted in mitral stenosis with regurgitation, tricuspid regurgitation, and severe pulmonary hypertension. After admission, the tumor was surgically removed. During the operation, it was found that the tumor originated from the mitral valve and invaded the valve annulus. How to place the artificial valve after the tumor was removed is the key to the success of the surgery. In this article, we aim to provide insights into the diagnosis, symptoms, and manifestations of primary cardiac angiosarcoma, as well as an alternative approach to intraoperative annulus reconstruction, and emphasize the importance of early diagnosis, treatment, and positive prognosis.